Your e-mail address is `registered` with your ISP (AOL) and, to the best of my knowledge, cannot be changed without a new account being formed.
I am confused by the apparent need to change your e-mail address to download the software as this is done from the suppliers` site or a CD is posted to you or perhaps both.
When you purchased the software you are likely to have provided your e-mail address for the key to be sent to - I presume you provided your address and not an incorrect one? The same applies if you registered on the site.
You will need to provide more information for any more help to be provided.