How do I change my name in Fortnite?

Hi, I've got a question. I play on pc, cellphone and ps4 fortnite. I want to change my display name now. I have learned that you can only change the display name on the Ps4 if you change the online ID. I don't want to do this because I want to change my name more often, but after the second change it will cost money. But if you change the display name on the Epic Games page, is the name only changed to PC and cell phone or is it also changed to Ps4?

I'm wondering why you play it on 3 devices because you can also just play it on a PC but ok it's actually very easy you register at the Epic Games page then go to your name above then go to your account and then you can change your name, password, email etc.