After googling, I found: run the command sparky-upgrade in a terminal window. That worked. (Sorry).
==> ORIGINAL post:
I am told updates exist, the back/forth gui "busy" indicator occurs (updating repositories), then a console window pops up, 20 lines quickly appear, that window disappears (and then the whole thing starts again.
If I choose "show changelog" (whatever that option is called, instead of "upgrade"), it shows a lot of upgrades that should occur. But, when I choose "upgrade" the back/forth busy indicator appears (updating repositories), then the console window which shows 20 lines and disappears.
I have to choose "exit" for this to stop.