Have you tried changing it through the console?
I didn't know there was a way to change it on the website.
Did this solve your problem?
Sorry this didn't help.
Great! Thanks for marking this as the answer.
How satisfied are you with this reply?
Thanks for your feedback, it helps us improve the site.
How satisfied are you with this response?
Thanks for your feedback.
Hello, when I was going to change my gamertag awhile back on the Xbox.com website, it did the same for me, like smwutches mentioned, I recommend doing it on the console.
Hi guys and girls, Im new to xbox and when i set it up i just picked any gamertag, But now i want to change with 800ms points way and was woundering will it reset all my online levels.
No, no it won't.