Old gamertag being displayed

The double gamertag is by design, as they transition over to the new gamertag system. Not all games will display the new gamertag system and as stated, your old gamertag will be displayed on 360 backwards compatible games. Any gamertag you create yourself,
is a custom gamertag.

changing gamertag does not change it on EA, even though they are still linked, it will display as your old gamertag name, i currently have 3 gamertags linked to my ea account too.

Hi. None of these helped me solve my problem, it still displays the old gamertag. Is there any other ways?

Hello, that feature will only be added to games in 2020. Your gamertag does contain the # but it won't display in games for now. Also it isnt confirmed whether old games will display the hashtag, all new games starting sometimes next year will display
it for sure

Hello, there is no need to contact support. Your son has the correct gamertag, which was changed under the new system. Games still use the old system and will display the old gamertag until 2020. Even then only new games and certain old games will support
the new system. There was an option to change the 'old system' gamertag while you were creating the new one but now it's too late to do it for free.