Oh, that's it! I'm running macOS 10.13 High Sierra. I got auto-updated to 14.2 and found its obtrusive alert windows intolerable, so I'm trying to go back to Avast 13.5
Now, here's something else weird-- I just downloaded Mac Security Free:
https://files.avast.com/mac/avast_free_mac_security.dmg [macOS 10.6/10.7/10.8] and installed 12.9-- but I just checked, and the app is actually 13.3
Man, Avast sure doesn't make it easy for a user! But I guess I've gotten where I wanted to be. And now I've turned off Automatic Program Updates in the Preferences-- so maybe I can go back to normal!
Thanks again, Asyn! You've been a big help!
Ken