Since MultiVersus has been out for a while and yet hasn't, chances are you'll boot up the game and find that you still have an outdated account linked to the game.
How to Create a WB Account in MultiVersus and Change WB Name (PS4, PS5, Xbox, PC)
This is mostly likely due to the game being cross-platform. Don't worry, though, you can work your way to cross-progression and even transfer all of your PlayStation progress over to Steam, or vice versa. Read on to learn how to link, unlink, and switch accounts in MultiVersus.
You cannot directly switch which MultiVersus account you are logged in with from an in-game menu. Instead, you can switch accounts in two ways: by switching platform accounts (e.g. logging in with a different Steam account), and by switching which Warner Bros Games account is linked to a particular Steam/Xbox/etc. account.
When you first launched MultiVersus, you were prompted to create a Warner Bros Games account. This may have happened back in 2022, so you may not remember ever doing so. That means there’s a good chance you created a separate Warner Bros account later on without realizing you already had one, and now you have separate accounts floating around on separate platforms or distributors. Don’t worry, there’s an easy fix.