Lost Administrator
I was given a old iMac by my work they gave me the passwords and I changed the password and all worked well. Today I changed the name of the the Admin to my name, then I clicked locked the window. The the admin name disappeared the old name came back and it says STANDARD below the name. When I click back on the lock it has no admin name and no password. I seem to have no administrator on the computer anymore. It is still running and open. If I turn it off or reboot it I am concerned it will be locked and I will not be able to open the computer at all. It is a late 2013 running iOS High Sierra 10.13.6 How do I set an Administrator?
iMac