Oops! *I forgot to mention this before*, but if you are logging into your W10 Pro, and you have another PC or laptop that's also running W10 Pro or W10 Home and both computers are using a Microsoft Account Login (the one that gives you access to the Microsoft App Store), if your 2nd computer has it's lock screen picture changed; it will
AUTOMATICALLY change back to whatever Lock Screen Picture you have on that 1st W10 computer on your home network!!
This is a Sync feature new to W10. It took me months to figure this out. If this is your case, and you or another family member, or a roommate has a W10 computer and you use your same Microsoft Account Login and Password on that computer, you cannot change your Lock Screen Picture on your W10 Pro computer!! if you do, W10 will change it back to whatever Lock Screen Picture is on that other W10 computer that pre-dates you adding that Pro computer into your Home network!
This also happens to be true with W10 Homegroups as well, unfortunately. Whether or not you are using Homegroups, the Sync feature overrides the desktop settings on that 2nd W10 Pro computer.
Hope this helps.
<<<BBJ>>>