Further pondering reminded me of what the problem was that eventually led me to select the wrong WiFi, a very strange problem:
My wife's computer was acting oddly, so I decided to restart it; there was no notification of the need to restart to finish installing a Windows update. The restart process began, and despite the lack of a notification, began the usual two-step update process, but it ran much faster than I had ever seen it. It was at the end of this odd supposed install of an update that the strangeness became very obvious.
Instead of seeing the usual log-on page, there were some pages rather similar to those that you see after a major update, but after logging on. I was given the choice of accepting or rejecting the use of perhaps two or three Microsoft items, whereupon I was then offered a choice of how to log on, using either a MS account or an email account. What the email account had to do with logging on, that I don't know.
I went to my computer, wrote down our email log-on password, entered it in the box on the other computer, whereupon the standard log-on page appeared, so I entered that password and waited until the process completed. I believe that I then chose the wrong WiFi, but perhaps it was chosen and connected automatically.That done, the next thing I did was go to Settings/Windows Update. Windows Update indicated that it had been unable to access that information as something else had been updating, and proceeded to obtain two updates.
While that was going on, I clicked on Update History, where I found not a single item for that date. When updating was ready, I restarted again, and this time the process ran as expected and finished at the log-on page. After waiting again, I rechecked Update History, where I saw the two updates as expected.