Windows 11’s desktop slideshow currently selects one folder and does not reliably include pictures stored inside its subfolders. There is no “include subfolders” switch in Settings > Personalization > Background.
The simplest workaround is to create one new folder, for example Pictures\Desktop Slideshow, and place copies of the photos you want displayed directly inside it. Then:
Right-click an empty area of the desktop and select Personalize.
Select Background.
Change Personalize your background to Slideshow.
Select Browse, then choose the new Desktop Slideshow folder.
Turn on Shuffle the picture order and choose how often the picture should change.
Unfortunately, if you want every photo from thousands of existing subfolders without copying them, you would need a third-party wallpaper application or a more technical workaround using file links. It is recommended that you use the single-folder method first, since it is easier to maintain and does not alter your original photo folders.
Thank you for your patience in reading, I hope this information has been helpful to you.
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