diff --git a/contracts/OwnerData.sol b/contracts/OwnerData.sol
index c2232b6..d59c620 100644
--- a/contracts/OwnerData.sol
+++ b/contracts/OwnerData.sol
@@ -15,9 +15,9 @@ import "@openzeppelin/contracts/token/ERC1155/IERC1155.sol";
  */
 contract OwnerData is Context, Ownable {
     string private constant SIGNED_MESSAGE = "Authorize to write your data to the contract";
-    address private immutable _signer;
-    address private immutable _costReceiver;
-    uint256 public cost;
+    address public signer;
+    address public serviceFeeReceiver;
+    uint256 public serviceFee;
 
     struct Data {
         address owner;
@@ -41,11 +41,11 @@ contract OwnerData is Context, Ownable {
     mapping(address => mapping(uint256 => bool)) private _publicTokens;
 
     event DataAdded(address indexed contractAddress, uint256 indexed tokenID, Data data);
+    event DataRemoved(address indexed contractAddress, uint256 indexed tokenID, uint256[] indexes);
 
     error TrusteeIsZeroAddress();
-    error CostReceiverIsZeroAddress();
+    error EmptyServiceFeeReceiver();
     error PaymentRequiredForPublicToken();
-    error IndexOutOfBounds();
     error InvalidParameters();
     error OwnerAndSenderMismatch();
     error SenderIsNotTheOwner();
@@ -53,28 +53,37 @@ contract OwnerData is Context, Ownable {
     error InvalidSignature();
 
 
-    constructor(address signer_, address costReceiver_, uint256 cost_) {
+    constructor(address signer_, address serviceFeeReceiver_, uint256 serviceFee_) {
         if (signer_ == address(0)) {
             revert TrusteeIsZeroAddress();
         }
-        if (costReceiver_ == address(0)) {
-            revert CostReceiverIsZeroAddress();
+        if (serviceFeeReceiver_ == address(0)) {
+            revert EmptyServiceFeeReceiver();
         }
-        _signer = signer_;
-        _costReceiver = costReceiver_;
-        cost = cost_;
+        signer = signer_;
+        serviceFeeReceiver = serviceFeeReceiver_;
+        serviceFee = serviceFee_;
     }
 
+    /// @notice add data to the token
+    /// @param contractAddress_ - the address of the contract
+    /// @param tokenID_ - the token ID
+    /// @param data_ - the data to add
     function add(address contractAddress_, uint256 tokenID_, Data calldata data_) external payable {
-        if (_publicTokens[contractAddress_][tokenID_] && msg.value < cost) {
+        if (_publicTokens[contractAddress_][tokenID_] && msg.value < serviceFee) {
             revert PaymentRequiredForPublicToken();
         }
         _addData(_msgSender(), contractAddress_, tokenID_, data_);
         if (msg.value > 0) {
-            payable(_costReceiver).transfer(msg.value);
+            payable(serviceFeeReceiver).transfer(msg.value);
         }
     }
 
+    /// @notice get data by contract address and token ID
+    /// @param contractAddress_ - the address of the contract
+    /// @param tokenID_ - the token ID
+    /// @param startIndex - the start index
+    /// @param count - the count of data
     function get(address contractAddress_, uint256 tokenID_, uint256 startIndex, uint256 count) public view returns (Data[] memory) {
         Data[] memory data = _tokenData[contractAddress_][tokenID_];
         if (startIndex > data.length) {
@@ -90,6 +99,10 @@ contract OwnerData is Context, Ownable {
         return result;
     }
 
+    /// @notice get data by contract address, token ID and owner
+    /// @param contractAddress_ - the address of the contract
+    /// @param tokenID_ - the token ID
+    /// @param owner_ - the owner address
     function getByOwner(address contractAddress_, uint256 tokenID_, address owner_) public view returns (Data[] memory) {
         Data[] memory data = _tokenData[contractAddress_][tokenID_];
         Data[] memory temp = new Data[](data.length);
@@ -107,20 +120,46 @@ contract OwnerData is Context, Ownable {
         return result;
     }
 
-    function remove(address contractAddress_, uint256 tokenID_, uint256[] calldata indexes_) external {
+    /// @notice remove data by indexes
+    /// @param contractAddress_ - the address of the contract
+    /// @param tokenID_ - the token ID
+    /// @param indexes_ - the indexes of the data to remove
+    function remove(address contractAddress_, uint256 tokenID_, uint256[] calldata indexes_) external onlyOwner {
         Data[] storage data = _tokenData[contractAddress_][tokenID_];
         for (uint256 i = 0; i < indexes_.length; i++) {
-            if (indexes_[i] >= data.length) {
-                revert IndexOutOfBounds();
-            }
             data[indexes_[i]].dataHash = new bytes(0);
         }
+        emit DataRemoved(contractAddress_, tokenID_, indexes_);
+    }
+
+    /// @notice the service fee of adding data
+    /// @param serviceFee_ - the service fee of adding data
+    function setServiceFee(uint256 serviceFee_) external onlyOwner {
+        serviceFee = serviceFee_;
     }
 
-    function setCost(uint256 cost_) external onlyOwner {
-        cost = cost_;
+    /// @notice the service fee receiver address
+    /// @param serviceFeeReceiver_ - the address of service fee receiver
+    function setServiceFeeReceiver(address serviceFeeReceiver_) external onlyOwner {
+        if (serviceFeeReceiver_ == address(0)) {
+            revert EmptyServiceFeeReceiver();
+        }
+        serviceFeeReceiver = serviceFeeReceiver_;
+    }
+
+    /// @notice the address of the signer
+    /// @param signer_ - the address of the signer
+    function setSigner(address signer_) external onlyOwner {
+        if (signer_ == address(0)) {
+            revert TrusteeIsZeroAddress();
+        }
+        signer = signer_;
     }
 
+    /// @notice set public tokens
+    /// @param contractAddresses_ - the addresses of the contracts
+    /// @param tokenIDs_ - the token IDs
+    /// @param isPublic_ - the flag of public token
     function setPublicTokens(address[] memory contractAddresses_, uint256[] memory tokenIDs_, bool isPublic_) external onlyOwner {
         if (contractAddresses_.length == 0 || contractAddresses_.length != tokenIDs_.length) {
             revert InvalidParameters();
@@ -130,6 +169,11 @@ contract OwnerData is Context, Ownable {
         }
     }
 
+    /// @notice add data with signature
+    /// @param contractAddress_ - the address of the contract
+    /// @param tokenID_ - the token ID
+    /// @param data_ - the data to add
+    /// @param signature_ - the signature
     function signedAdd(address contractAddress_, uint256 tokenID_, Data calldata data_, Signature calldata signature_) external {
         _validateSignature(signature_);
         address account = data_.owner;
@@ -175,7 +219,7 @@ contract OwnerData is Context, Ownable {
             signature_.r,
             signature_.s
         );
-        if (reqSigner != _signer) {
+        if (reqSigner != signer) {
             revert InvalidSignature();
         }
     }
diff --git a/test/owner_data.js b/test/owner_data.js
index f0b71a2..a551601 100644
--- a/test/owner_data.js
+++ b/test/owner_data.js
@@ -558,7 +558,7 @@ contract("OwnerData", async (accounts) => {
 
     it("test set cost negative value", async function () {
         try {
-            await this.ownerDataContract.setCost(
+            await this.ownerDataContract.setServiceFee(
                 web3.utils.toWei("-0.015", "ether"),
             );
         } catch (error) {
diff --git a/truffle-config.js b/truffle-config.js
index 59a7a56..d5cbe72 100644
--- a/truffle-config.js
+++ b/truffle-config.js
@@ -27,6 +27,7 @@ let {
     mainnet_mnemonic,
     mainnet_endpoint,
     goerli_endpoint,
+    sepolia_endpoint,
     etherscan_api,
 } = secret;
 
@@ -49,17 +50,11 @@ module.exports = {
         // options below to some value.
         //
         mainnet: {
-            // provider: function () {
-            //     return new HDWalletProvider(mainnet_mnemonic, mainnet_endpoint);
-            // },
             provider: function () {
-                return new HDWalletProvider(
-                    "0b7216547a5bb34a1a779e0233dd4ce2548d9f50d46ae541bf93bbbd84b9596b",
-                    mainnet_endpoint
-                );
+                return new HDWalletProvider(mainnet_mnemonic, mainnet_endpoint);
             },
-            // gas: 3500000,
-            // gasPrice: 90000000000, // 20 gwei (in wei) (default: 100 gwei)
+            gas: 3500000,
+            gasPrice: 90000000000, // 20 gwei (in wei) (default: 100 gwei)
             network_id: 1,
         },
         development: {
@@ -67,29 +62,19 @@ module.exports = {
             port: 7545, // Standard Ethereum port (default: none)
             network_id: "*", // Any network (default: none)
         },
-        sepolia: {
+        goerli: {
             provider: function () {
-                return new HDWalletProvider(
-                    "45c7bfbcc4f9a5387e03798f763dafb91aa305f8f905547227c6cbfd8da0acbe",
-                    "https://rpc.ankr.com/eth_sepolia"
-                );
+                return new HDWalletProvider(mnemonic, goerli_endpoint);
             },
-            gas: 4500000,
-            network_id: 11155111,
-        },
-        goerli: {
-            // provider: function () {
-            //     return new HDWalletProvider(mnemonic, goerli_endpoint);
-            // },
             // gas: 6000000,
+            network_id: 5,
+        },
+        sepolia: {
             provider: function () {
-                return new HDWalletProvider(
-                    "45c7bfbcc4f9a5387e03798f763dafb91aa305f8f905547227c6cbfd8da0acbe",
-                    "https://rpc.ankr.com/eth_goerli"
-                );
+                return new HDWalletProvider(mnemonic, sepolia_endpoint);
             },
-            // gas: 4500000,
-            network_id: 5,
+            // gas: 6000000,
+            network_id: 11155111,
         },
         // Another network with more advanced options...
         // advanced: {