How to Change the Credentials for SQL Server Reporting Services Account
If the account that is used for the SQL Server Reporting Services account changes in System Center 2012 – Service Manager, you must change the credentials for the account. Use the following procedure to change the credentials for the SQL Server Reporting Services account.
To change the credentials for the SQL Server Reporting Services account
On the computer hosting SQL Server Reporting Server (SSRS), start a browser, and connect to http://<server name>/reports.
On the SQL Server Reporting Services Home page, double-click Service Manager, and then double-click DWStagingAndConfig.
In the Connect using area, click Credentials stored securely in the report server, type the current credentials in the User name and Password boxes, and then click Apply.
In the browser tool bar, click the Back button to return to the Service Manager page.
Repeat steps 2 and 3 for the remaining Service Manager data sources.