I just found out that Z is undo and shift-z is redo on my comp...???

...But how do I change the settings or where do I find settings?

Thanks for helping me :-))

by the way I let a friend of mine use my comp a week ago using maya and he installed maya 5.0 on it, maybe he changed the settings? I can't reach him right now so please let me know how to change settings:-))

Thanks guys!!