Computer Automatically Changes the Wallpaper to the Previous Owner's Vacation Photos

The likely causes are an old slideshow folder, a wallpaper app, or personalisation settings syncing from an account still connected to the PC.

Try these in order:

1. Set a fixed local picture. Go to Settings > Personalisation > Background and select Picture, not Slideshow or Windows Spotlight. Browse to an image in your own Pictures folder rather than selecting an old thumbnail.
2. Check which account you’re using. Open Settings > Accounts > Your info. If it shows the previous owner’s Microsoft account, create your own Windows user account rather than continuing to use theirs. Don’t delete the old profile until you’ve backed up your own files.
3. Temporarily turn off personalisation sync. In Windows 11, look under Accounts > Windows backup > Remember my preferences > Personalisation. In Windows 10, check Accounts > Sync your settings > Theme. Set your wallpaper again and restart.
4. If it still returns, check Task Manager > Startup apps for a wallpaper changer or desktop-customisation app. Disable the relevant app and test another restart.

You don’t have to find and delete the old photos to stop them appearing; you need to stop whatever is selecting them. If this is a second-hand PC that was never reset, backing up your files and doing a clean Windows setup is also worth considering so you aren’t inheriting the previous owner’s accounts and software.