Finder settings disappear with every restart: icons rearranged, background/desktop reset, etc. Why?

If I arrange the files/icons on my hard drive in a certain way that I prefer, and then set a desktop background picture, and do various customizations of the Finder, and then restart the computer -- poof, it all goes away after restart, and the icons are now all a different size, arranged in a standard alphabetical/default row, the desktop picture is now gone, etc. etc. This happens every time I restart. Drives me crazy.

What is happening? Why won't any changes that I make to the Finder persist from restart to restart? This has never happened to me before, on any computer, and any version of MacOS.

El Capitan 10.116, on an iMac.