Hi, I'm John! I will help you with this.
To set your lock screen background to Slideshow:
- Open Settings. Go to Personalization > Background.
- Under Personalize your background, choose Slideshow.
- Select the folder containing the pictures you want to use.
- Choose how often the picture changes and whether it should shuffle.
If the option isn’t appearing or nothing happens after selecting the folder, let me know what you see on your end, any error message or if the slideshow option is grayed out.
Click "Add comment" to let me know.
Regards,
John J.D.