Hello,
You can personalize the looks of your Windows 10 computer screen by changing the wallpaper of its lock and desktop screen. To sort out your concern, we suggest that you check if the Background settings of the Lock screen is set to Windows spotlight. This option will display random photos from Bing and appears on the screen when your computer is locked.
To do this, you may click Start > Settings > Personalization > Lock screen. Under the Background section, click the menu bar, and then select Windows spotlight.
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