Sharepoint site showing system account instead of my username on the top right corner.

Question: http://social.technet.microsoft.com/Forums/en-US/sharepointadmin/thread/8d8d9b30-0995-47ba-96e8-7b52872664f3

Resolution: http://technet.microsoft.com/en-us/library/cc288427.aspx

Change the application pool identity for a Web application (Windows SharePoint Services)

1. On the top navigation bar, click Operations.

2. On the Operations page, in the Security Configuration section, click Service accounts.

3. On the Service Accounts page, in the Credential Management section, under Select the component to update, select Web application pool.

4. In the Web service list, click a Web service.

5. In the Application pool list, click the application pool that you want associated with the Web application.

6. Under Select an account for this component, select one of the following:

   • Predefined   Select this option to use a predefined account, such as the Network Service account or the Local Service account.

   • Configurable   Select this option to specify a different account.

7. Click OK.