Hello! First post on this fantastic forum which has sorted me out a number of times. However I can't find a solution for this issue , so I hope someone can help me!

Following a rollback to 8.1 after installing the full release of Windows 10 I've been unable to change the account pictures, lock screens or picture passwords for any user. I've tried the following.

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It's driving me a bit nuts now! If anyone has any suggestions I'd be very grateful!