diff --git a/purchase_operating_unit/__manifest__.py b/purchase_operating_unit/__manifest__.py
index a46cd5db9b..1eac69b4e6 100644
--- a/purchase_operating_unit/__manifest__.py
+++ b/purchase_operating_unit/__manifest__.py
@@ -7,7 +7,7 @@
     "name": "Operating Unit in Purchase Orders",
     "summary": "Adds the concecpt of operating unit (OU) in purchase order "
     "management",
-    "version": "15.0.1.2.0",
+    "version": "17.0.1.0.0",
     "author": "ForgeFlow, "
     "Serpent Consulting Services Pvt. Ltd.,"
     "Odoo Community Association (OCA)",
diff --git a/purchase_operating_unit/models/account_move.py b/purchase_operating_unit/models/account_move.py
index 17e4933d6e..75a6149e31 100644
--- a/purchase_operating_unit/models/account_move.py
+++ b/purchase_operating_unit/models/account_move.py
@@ -2,17 +2,13 @@
 # - Jordi Ballester Alomar
 # Copyright 2015-17 Serpent Consulting Services Pvt. Ltd. - Sudhir Arya
 # License LGPL-3.0 or later (https://www.gnu.org/licenses/lgpl.html).
-from odoo import _, api, fields, models
+from odoo import _, api, models
 from odoo.exceptions import ValidationError
 
 
 class AccountMove(models.Model):
     _inherit = "account.move"
 
-    purchase_ou_domain = fields.Many2many(
-        comodel_name="purchase.order", compute="_compute_purchase_ou_domain"
-    )
-
     # Load all unsold PO lines
     @api.onchange("purchase_vendor_bill_id", "purchase_id")
     def _onchange_purchase_auto_complete(self):
@@ -27,15 +23,6 @@ def _onchange_purchase_auto_complete(self):
             self.operating_unit_id = purchase_id.operating_unit_id.id
         return super()._onchange_purchase_auto_complete()
 
-    @api.depends("operating_unit_id")
-    def _compute_purchase_ou_domain(self):
-        for rec in self:
-            rec.purchase_ou_domain = (
-                self.env["purchase.order"]
-                .sudo()
-                .search([("operating_unit_id", "=", rec.operating_unit_id.id)])
-            )
-
 
 class AccountMoveLine(models.Model):
     _inherit = "account.move.line"
diff --git a/purchase_operating_unit/models/purchase_order.py b/purchase_operating_unit/models/purchase_order.py
index 07810dfe0a..132e41944c 100644
--- a/purchase_operating_unit/models/purchase_order.py
+++ b/purchase_operating_unit/models/purchase_order.py
@@ -9,27 +9,19 @@
 class PurchaseOrder(models.Model):
     _inherit = "purchase.order"
 
-    READONLY_STATES = {
-        "purchase": [("readonly", True)],
-        "done": [("readonly", True)],
-        "cancel": [("readonly", True)],
-    }
-
     operating_unit_id = fields.Many2one(
         comodel_name="operating.unit",
         string="Operating Unit",
-        states=READONLY_STATES,
         default=lambda self: (
-            self.env["res.users"].operating_unit_default_get(self.env.uid)
+            self.env["res.users"]._get_default_operating_unit(self.env.uid)
         ),
     )
 
     requesting_operating_unit_id = fields.Many2one(
         comodel_name="operating.unit",
         string="Requesting Operating Unit",
-        states=READONLY_STATES,
         default=lambda self: (
-            self.env["res.users"].operating_unit_default_get(self.env.uid)
+            self.env["res.users"]._get_default_operating_unit(self.env.uid)
         ),
     )
 
diff --git a/purchase_operating_unit/tests/test_purchase_operating_unit.py b/purchase_operating_unit/tests/test_purchase_operating_unit.py
index 3cb596fd8e..14aedf2852 100644
--- a/purchase_operating_unit/tests/test_purchase_operating_unit.py
+++ b/purchase_operating_unit/tests/test_purchase_operating_unit.py
@@ -10,55 +10,56 @@
 
 
 class TestPurchaseOperatingUnit(common.TransactionCase):
-    def setUp(self):
-        super().setUp()
-        self.ResUsers = self.env["res.users"]
-        self.PurchaseOrder = self.env["purchase.order"]
-        self.AccountInvoice = self.env["account.move"]
-        self.AccountAccount = self.env["account.account"]
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.ResUsers = cls.env["res.users"]
+        cls.PurchaseOrder = cls.env["purchase.order"]
+        cls.AccountInvoice = cls.env["account.move"]
+        cls.AccountAccount = cls.env["account.account"]
         # company
-        self.company = self.env.ref("base.main_company")
+        cls.company = cls.env.ref("base.main_company")
         # groups
-        self.group_purchase_user = self.env.ref("purchase.group_purchase_user")
+        cls.group_purchase_user = cls.env.ref("purchase.group_purchase_user")
         # Main Operating Unit
-        self.ou1 = self.env.ref("operating_unit.main_operating_unit")
+        cls.ou1 = cls.env.ref("operating_unit.main_operating_unit")
         # B2B Operating Unit
-        self.b2b = self.env.ref("operating_unit.b2b_operating_unit")
+        cls.b2b = cls.env.ref("operating_unit.b2b_operating_unit")
         # Partner
-        self.partner1 = self.env.ref("base.res_partner_1")
+        cls.partner1 = cls.env.ref("base.res_partner_1")
         # Products
-        self.product1 = self.env.ref("product.product_product_7")
-        self.product2 = self.env.ref("product.product_product_9")
-        self.product3 = self.env.ref("product.product_product_11")
+        cls.product1 = cls.env.ref("product.product_product_7")
+        cls.product2 = cls.env.ref("product.product_product_9")
+        cls.product3 = cls.env.ref("product.product_product_11")
         # Account
-        payable_acc_type = self.env.ref("account.data_account_type_payable").id
-        self.account = self.AccountAccount.search(
-            [("user_type_id", "=", payable_acc_type)], limit=1
+        cls.account = cls.AccountAccount.search(
+            [("account_type", "=", "liability_payable")], limit=1
         )
         # Create users
-        self.user1_id = self._create_user(
+        cls.user1_id = cls._create_user(
             "user_1",
-            [self.group_purchase_user],
-            self.company,
-            [self.ou1],
+            [cls.group_purchase_user],
+            cls.company,
+            [cls.ou1],
         )
-        self.user2_id = self._create_user(
+        cls.user2_id = cls._create_user(
             "user_2",
-            [self.group_purchase_user],
-            self.company,
-            [self.b2b],
+            [cls.group_purchase_user],
+            cls.company,
+            [cls.b2b],
         )
-        self.purchase1 = self._create_purchase(
-            self.user1_id,
-            [(self.product1, 1000), (self.product2, 500), (self.product3, 800)],
+        cls.purchase1 = cls._create_purchase(
+            cls.user1_id,
+            [(cls.product1, 1000), (cls.product2, 500), (cls.product3, 800)],
         )
-        self.purchase1.with_user(self.user1_id).button_confirm()
-        self.invoice = self._create_invoice(self.purchase1, self.partner1, self.account)
+        cls.purchase1.with_user(cls.user1_id).button_confirm()
+        cls.invoice = cls._create_invoice(cls.purchase1, cls.partner1, cls.account)
 
-    def _create_user(self, login, groups, company, operating_units):
+    @classmethod
+    def _create_user(cls, login, groups, company, operating_units):
         """Create a user."""
         group_ids = [group.id for group in groups]
-        user = self.ResUsers.with_context(**{"no_reset_password": True}).create(
+        user = cls.ResUsers.with_context(**{"no_reset_password": True}).create(
             {
                 "name": "Chicago Purchase User",
                 "login": login,
@@ -72,7 +73,8 @@ def _create_user(self, login, groups, company, operating_units):
         )
         return user.id
 
-    def _create_purchase(self, user_id, line_products):
+    @classmethod
+    def _create_purchase(cls, user_id, line_products):
         """Create a purchase order.
         ``line_products`` is a list of tuple [(product, qty)]
         """
@@ -87,18 +89,19 @@ def _create_purchase(self, user_id, line_products):
                 "date_planned": time.strftime(DEFAULT_SERVER_DATETIME_FORMAT),
             }
             lines.append((0, 0, line_values))
-        purchase = self.PurchaseOrder.with_user(user_id).create(
+        purchase = cls.PurchaseOrder.with_user(user_id).create(
             {
-                "operating_unit_id": self.ou1.id,
-                "requesting_operating_unit_id": self.ou1.id,
-                "partner_id": self.partner1.id,
+                "operating_unit_id": cls.ou1.id,
+                "requesting_operating_unit_id": cls.ou1.id,
+                "partner_id": cls.partner1.id,
                 "order_line": lines,
-                "company_id": self.company.id,
+                "company_id": cls.company.id,
             }
         )
         return purchase
 
-    def _create_invoice(self, purchase, partner, account):
+    @classmethod
+    def _create_invoice(cls, purchase, partner, account):
         """Create a vendor invoice for the purchase order."""
         invoice_vals = {
             "purchase_id": purchase.id,
@@ -111,7 +114,7 @@ def _create_invoice(self, purchase, partner, account):
             "active_model": "purchase.order",
         }
         res = (
-            self.env["account.move"]
+            cls.env["account.move"]
             .with_context(**purchase_context)
             .create(invoice_vals)
         )
diff --git a/purchase_operating_unit/views/account_move_view.xml b/purchase_operating_unit/views/account_move_view.xml
index 028c677b79..ef275fe063 100644
--- a/purchase_operating_unit/views/account_move_view.xml
+++ b/purchase_operating_unit/views/account_move_view.xml
@@ -7,10 +7,9 @@
         <field name="inherit_id" ref="purchase.view_move_form_inherit_purchase" />
         <field name="arch" type="xml">
             <xpath expr="//field[@name='purchase_id']" position="attributes">
-                <attribute name="domain">[('id', 'in', purchase_ou_domain)]</attribute>
-            </xpath>
-            <xpath expr="//field[@name='purchase_id']" position="after">
-                <field name="purchase_ou_domain" invisible="1" />
+                <attribute
+                    name="domain"
+                >['|',('operating_unit_id', '=', operating_unit_id),('operating_unit_id', '=', False)]</attribute>
             </xpath>
         </field>
     </record>
diff --git a/purchase_operating_unit/views/purchase_order_view.xml b/purchase_operating_unit/views/purchase_order_view.xml
index 13c2b00da5..9377ee3b85 100644
--- a/purchase_operating_unit/views/purchase_order_view.xml
+++ b/purchase_operating_unit/views/purchase_order_view.xml
@@ -22,10 +22,12 @@
                 <field
                     name="requesting_operating_unit_id"
                     groups="operating_unit.group_multi_operating_unit"
+                    readonly="state in ['cancel', 'done', 'purchase']"
                 />
                 <field
                     name="operating_unit_id"
                     groups="operating_unit.group_multi_operating_unit"
+                    readonly="state in ['cancel', 'done', 'purchase']"
                 />
             </field>
             <field name="order_line" position="attributes">