Yeah, the system has been rock solid since!
Hey thanks! Of course I didn’t look for the “How to…” in installation instructions, and I looked for the answer here! Every once in a while you can search high and low with all kinds of ways of asking, only to find nothing, and then you find the answer in a posting with a completely irrelevant title! You would think “systemd, change boot menu” would be a sure hit! 
Just wait, I’m going to change it, and reboot to get a Windows login screen, even though I haven’t used Windows at all in over a decade, and never had it on any of the drives in this PC!! 
!