When changing options there's usually a button that says:
'Apply', and I've noticed that if you
don't click it the computer will
not apply any changes you have made.
Alternatively, it could be a program on your OS that's keeping the changes from being made; if that's the case then you have to find the program that's doing it and set it to 'Allow changes' or something to that effect.
I've had computers with programs installed like that and wasn't able to do much about it.
I hope I helped you to save the mouse!
