Changing System Name on Mac Login Screen

This seems to be a little known thing, but it's easy when you know how. Everyone points you to Users and Groups, which is the main place to change the system name. But if you see an old name on the login screen, this is changed under Security and Privacy-->General-->Set Lock Message. It's not really your system name. It's just a Lock Message that Apple set automatically somewhere along the line to the system name, and when you did a Time Machine restore to your new machine, it did not change it. Super easy when you know how. But you could spend hours trying to work it out. I did.