Switch Fortnite account to another Ps4 user?

Have some questions about playing Fortnite on Ps4.

I have been playing Fortnite on a Ps4 user for a while, but now I have a new user and want to continue playing with my account where I spent money.

How can I log out of an account in the game?

Can I be logged in to multiple users with the same account?

I've also created a user a couple of times, but I always had to start over because my Fortnite username and password didn't work. But, for example, for mobile phones, my access data is still working.

Why is that?

You can connect Pro Fortnite Account only 1x Playstation 1xXbox and then hold switch you can't play on a second Olaystation profile with your other Fortnite account, but earlier that was done by Account Trading.