Is it possible to change the ext within some buttons?

Is it possible to change the ext within some buttons?

The buttons in question are-
1) SIGN UP on the registration form ..... can I use the word "Register" instead and if so how do i go about doing it?
2) Can I change the "SIGN UP" button on the final page to ..."CONFIRM" ...... this is the button next to the silly PAY Pal phrase that I am n ot able to get rid of yet (work in progress)

Peter