How do i change my classic gamertag into my new 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?

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.

Hi J20gyv, my name is Rodrigo. I'm an Independent Advisor and a member of the Microsoft community and I'd love to assist you today.

I am sorry to hear that.

Please, try changing it on your XBOX One console.

Press the Xbox button on your controller, then select System > Settings > Personalization > My profile > Customize profile.

Select your Gamertag, then select it again to type a new Gamertag.

It may update your current Gamer Tag.

Depending on how you changed your tag, you can have a new gamertag as well as a classic gamertag. The classic tag would show up anywhere that the new gamertag system is not in place. The only way to fix it is to change it again.

i don’t want to change the suffix, i want to change my classic gamertag while keeping the same ‘new format’ gamertag