Scrivener runs in background

The other day, Scrivener, for no reason I’m aware of, began running in the background. It took me a while to discover it, but when I went to uninstall the program before re-installing it, hoping that might solve my problem, I got an error message saying the program was running and I needed to close it. Sure enough, there it was on Task Manager under background programs.

Anyone know how I make it return to foreground operation?