I always look on the first page or two at the bottom and in tiny little letters is "subscription info". Usually there is an address, email or phone number to change address.
Shortbun, I just went through this in Oct. We get several magazines ourselves and the beauty shop gets them also. I had a few magically change (???) and went to the websites on the rest.
Used to I thought there was an 800 # to call inside the magazine under subscription info but alas, I could not find any info like that this time.