This article tells you what to do if you find that you cannot change lock screen picture on Windows 10 computer because the lock screen setting in PC settings is in uneditable mode, as shown in the following screen shot.
Video guide on what to do when you cannot change lock screen picture on Windows 10:
Step 2: Find and open the setting named "Prevent changing lock screen image".
For your information, it is located in Computer Configuration/Administrative Templates/Control Panel/Personalization.
Step 3: Do not configure this setting.
As the setting's window opens, choose Not Configured and tap OK.
Tip: The other alternative method is to disable this setting. In other words, select Disabled and click OK in the window above.
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