Just a little info for you from my recent experience with forwarding mail.
I tried to change my address via the USPS website but they actually ask you for a credit card at the end so that they can verify the address on file with the CC company with the address you are changing your address from to make sure it is you. I think they charge maybe a dollar to verify the address, just enough to get the info from the credit card company.
Most people do not know until the very end of doing it online that they want a credit card. I almost did it but then decided not to give out my CC number to the PO online (Yeah, I know I still am a little funny that way...of course if it was Belk or Macy's I would have no problem ).
Just thought I would give you that info re: how to change addresses online.