Laptop & PC traded user accounts

[Yago]

Hi,

My user account has migrated from my PC to my child's laptop & is usable on both machines. The administration account moved from my child's laptop to my PC & it is no longer on the laptop sign-in screen but it's on my PC's sign-in screen. When I type in the pin number for the laptop's administration account on my PC it goes to a black screen & freezes & I have to restart it to sign in on my user account. I would like to put things back the way they were but I don't know how. ​

Any help would be greatly appreciated,
Yago