To change the login credentials
Select the desired SQL Server schema.
On the Schema menu, click Change Login Credentials.
The Change Login Credentials dialog box appears.
Choose one of the following authentication methods to authenticate:
Windows Authentication: If the Windows logon credentials are added as a user account in the SQL Server Management Studio, select Windows Authentication.
SQL Server Authentication: If the logon credentials to the selected host are different from the Windows credentials, select SQL Server Authentication. Enter the login credentials in the Login User and Password fields for the selected SQL Server.
Click OK.
The login credentials are changed.