hogfanfs
After you are logged in, to the left is a box labled "Contact Info", at the bottom of this box is a link to "Update your E-mail"
That will allow you to change your email on your magazine account, but not on your forum account. I've been trying to change mine for about a year. I sent a message to Aaron about it. He answered it after a while, but it had been so long that I missed his message. I responded but haven't gotten an answer back. That was two months ago.
Good luck.