how to activate and deactivate the standard tool bar icons in a standard transaction code?

Hi Team,

can you  tell me  how can i activate and deactivate the standard tool bar icons in a standerd transaction code? for ex if i open the MM03 transaction by giving some material no by default the standard tool bar icon "EXIT" is in disable mode, so how can i enable that icon functionality, i tried by opening the SYSTEM->STATUS->GUI STATUS-> STANDARD TOOL BAR under function keys option , when i tried to make change it is asking access key, here my doubt is can't activate and deactivate this icon functionality in any program?

Thanks in advance.

venkat.