How can I change customize classic gamertag after already changing gamertag

So you said I can change my classic gamertag. How do I change that after already changing my gamertag or do I have to change my entire gamertag again to change the classic one?

Hi,

You cannot change the suffix that was added to your gamertag. If you'd like to change how the classic gametag appears for locations that don't support modern gamertags, you can se the "Customize classic gamertag" option when reserving your gamertag.
NOTE: A suffix is added when that exact gamertag is already registered. If you enter a unique gamertag, no suffix will be added.

Thanks

I'm trying to change my classic gamertag which is the one you see in games. My classic gamertag got changed and my Xbox One and Xbox App gamertag stayed the same (the Xbox One gamertag is the ones they added with the new gamertag system).

My Xbox One gamertag is different to my in-game gamertag and I want my classic gamertag to be changed. You can only change your classic gamertag on the Xbox One console, I have tried using the other ways and you can only change your Xbox Gamertag, not your
classic gamertag.

The reason I want to change my classic gamertag is that the classic gamertag can be fifteen characters and the Xbox One gamertag can only be 12 characters. If I use the other ways to change my gamertag it limits me to 12 characters and sets both my gamertags
to that.

Thank you for replying! I noticed that i have to pay and im fine with it, but i am fine with the gamertag i have currently ( the one with the discord #) and i just want to change the classic gamertag ( the one that shows in game) but in order to change
the classic one i have to choose a new gamertag ( with the #) but i dont want to do that, i tried retyping the one im already using but it says i own it and u cant change it.

Thank you for replying! I noticed that i have to pay and im fine with it, but i am fine with the gamertag i have currently ( the one with the discord #) and i just want to change the classic gamertag ( the one that shows in game) but in order to
change the classic one i have to choose a new gamertag ( with the #) but i dont want to do that, i tried retyping the one im already using but it says i own it and u cant change it.

Well, if I understood you well, the thing is you are considering the two gamertags as something different, but at the end you only have one, not two, so you cannot change "only one". How the gamertag shows in game depends on how the new GT# system
has been managed by developers anyway (not all games are doing the same right now).

So the one you call GT# is actually the only gamertag you have and can manage/change. How it shows in game and everywhere else, for the time being and untill all systems/applications are aligned to the new system, really depends on how it was implemented
in that specific case.