How do you change information on your xbox live membership?

When I signed up for xbox live i put in my age and all that crap. I registered myself under 18 because there was no restriction on downloading for people under 18. Now there is restrictions and I know my mom doesnt care so I wanted to change the age on my profile and I don't know how. I need to do it through xbox.com's xbox marketplace option not through the console as i am moving.How do you change information on your xbox live membership?i had the same problem call 1-800-4MY-XBOX and talk to them they will walk you through it