How do i change my age to 18 on my xbox live gold account when i already mady my account?

im trying to do this cause it wont let me download this demo and i have already changed the restrictions to allowed-What do i do?-help!How do i change my age to 18 on my xbox live gold account when i already mady my account?Same thing happens to me when I try to get the DMC 4 demo. you can't do anything. I changed the windows live ID, but it messed me up even further. You have to delete your account and make a new one, but you'll lose all of your achievements in the process.