Changed gamertag on one account and it changed on a different account.

aagsmith answered correctly, but there is a way to get your Gamertag on your old account; you can change your new account to a different Gamertag, and then change your old account's Gamertag to your desired one.

what i would do is get a few microsoft point cards, change the gamertag of account 1 to a different gamertag, then change the gamertag of account 2 to the one you want. was this helpful?

Creating a new account and changing the gamertag. However, when I tried to change my original account's gamertag to the new one, it was still unavailable. It seems that even if I use the gamertag on a different account, it remains locked.

Ok. I'm a little confused about how you say his gamertag is listed as an adult because it's your gamertag. However, here's the steps to follow.

1. When the console is loaded select Add Account and enter in your email/password info for your account. If you don't already have one, you'll need to create one.

2. Head to the top left corner of the screen and select the gamertag(s) listed there and follow the instructions in step one.

3. Go to Settings either from the dash if you see the option or by saying Xbox Go To Settings.

4. Scroll to the right until you see Add to Family. Select it and then add the gamertag(s) you want to add to the Family.

5. In order to add your tag to the Family, someone else will need to be logged in and add your tag.

Now you're done.

Ok, now I understand. Follow the steps located at the link I'm posting for how to change the email address associated with the gamertag. The easiest option to do this will be on the 360. Once done, you will have freed up the email address that is currently
on it so you can create your own gamertag.

support.xbox.com/.../change-xbox-live-account-info

However, be aware that you cannot change the age of the gamertag once it's been set. This means that if the tag is currently adult it cannot be changed to a child account.