I need you to update your GamerTag & Username.
To update your GamerTag, click "About Me" on your profile (directly above), then click the yellow pencil next to "GamerTag", update it, then "Save".
To update your Username, click "Help Desk" on the top right corner, then click "Request Login Name Change", type in your new GamerTag exactly how it is spelled, then send/submit the request.
Thank you.