To
change tab text, you must have at least one of the following privileges:
When you first add a tab to a page, the text displayed on the tab defaults to New Tab. You can change this text to describe the contents of the tab.
Alternatively, you can also change the appearance of a tab by creating images for the tab. For information about how to do this, see Applying images to a tab. If you provide images for a tab, the tab text is used as rollover text—that is, it displays when the user moves the cursor over the tab.
To
change tab text, you must have at least one of the following privileges:
Manage All privileges on the page group to which the page belongs
Manage privileges on the page
Manage privileges on the tab
Manage global privileges on All Pages
If you have full customization privileges on a page, you can change the text of your own tabs when you customize the page; you cannot change the text of tabs that you did not add yourself.
To change tab text:
Go to the page with which you want to work.
Switch to Edit mode.
Click 
on the tab for which you want to change the text.
In the Display Name field, enter the text that you want to display in the tab.
Click OK to return to the page.