Below the preview section, you will see a “Background” section with multiple options for customizations. Click on the dropdown box under “Background” section. There are three options to choose a lock screen background – Windows spotlight, picture and slideshow. In order to setup a slideshow, choose “Slideshow” from the dropdown.

• As you know Windows 10 allows users to set pictures slideshow as Desktop background as well as Lock Screen background. You can select desired folders containing images and set the slideshow as the background of Desktop and Lock Screen using Settings - Personalization - Background and Lock Screen pages.
• Download this app from Microsoft Store for Windows 10, Windows 10 Mobile, Windows 10 Team (Surface Hub), HoloLens. See screenshots, read the latest customer reviews, and compare ratings for SlideShow.

Photos for Mac does not shuffle photos.

But you could use the screensaver to show your album shuffled.

Windows 10 Shuffle Slideshow

• Open the System Preferences > Desktop & Screensaver.
• Select one of the photo templates for the screensaver in the left column.
• Set the source in the right column to 'Photo Library'; wait until your photos Library appears, select your album.
• Enable the checkmark 'Shuffle Slide order'.
• Then start the screensaver.

Or use an Apple Script to shuffle the photos in your album every time before you start the slideshow. See this user tip:

Slideshow Shuffle Windows 10

Aug 7, 2016 4:04 AM