I added a bit to my previous post just as you put in yours.

I appreciate your thorough instructions, but I'm way too insecure to try any of them.
Even if I were able to muddle way through the mechanics of, say, setting up another 'account', just as here, I wouldn't have a clue what to do with it. (So what's the point of even trying?)
I'd rather have a machine which operates marginally rather risk one that doesn't operate at all. That'd take me right back to DOS days, when I'd just sit there watching the C-prompt flashing and not having clue how to go any further and never did learn how. (That's why I got into Macs in the first place. Now I'm right back where I was 30 years ago ... and I don't like it.)