I would like to change my name in Fortnite via xbox one but do not know how I know that it works via Microsoft but do not know how
You don't do that via Microsoft either, but via the developer's settings, in this case Epic Games.
To do this, go to the Epic Games page on the Internet, log in, go to the account settings and rename yourself there.
For the first time you should check your grammar.
Secondly, you have to pay 10 euro to change your Xbox name, to change it go to your profile via the Xbox button (called the Xbox menu) and then you should be able to change your Xbox gamertag anywhere
I play over xbox but the name is still in-game because my Microsoft name is so called
No, you can still change that in Epic Games
