One of may apps (magic Jigsaw Puzzles) recently updated. Since the update, the app seems to change my Lock Screen background form "Windows Spotlight" to "Picture." No matter how many times I set the background to "Spotlight," the next time I see my lock scree, it has an app-uppliedpictue insteadt. The app doesn't automatically start at startup (I checked that), and, following some Windows adv ice, I cleared the appropriate user fil under my account. I also tried disabling Sync; neither has helped what's going on, and how do I stop this?