How to Change your Tab Name
1. Go to Edit Page
Visit your Facebook page wall and click the Edit Page button in the upper right hand corner of the window.
Click on the Apps tab on the left hand side of the window.
2. Edit Settings for App
Find the App name in your list. This is usually Static IFRAME Tab. Click on the Edit Settings link under the App name.
Enter your new tab name in the Custom Tab Name field and click Save.