Hi Miodrag.
It is possible that the domain user account was added to the local Administrators group on PC A that give the user Admin rights and permission on that PC. If the same was not done on the new PC then the user would have standard user rights and permissions.
If the PC is Azure Active directory joined, the user that joins the PC to AAD is granted admin privileges on that PC. If the same user logs into another PC that was joined to AAD by a different user then the ID would not have Admin privileges on that PC.
I hope that helps!
Ed Gallagher
UpTime CNS, MVP