How to change age on xbox live?

I share an xbox live account with my 11 year old brother. My dad and brother created the accoun and put my brothers age so it is a child account not a adult one. I have just noticed this because i cant go on faceboo, msn and twitter ... So i searched on the web and it says facebook ... is not available to child accounts. Pleeeeeeeeeeeeeeeeeeese !!!!!!! Help !!!!How to change age on xbox live?in account management there is a button some place that lets you upgrade to adult account. if you are 18 years old, the button should be highlighted, press it and bingo

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