If you’re in full-screen view, you need to exit it to change settings. Move your pointer to the top of the screen, and then click the Full Screen button that appears in the top-right corner.
Do one of the following:
Select the slideshow in the Source list, click the Settings button in the toolbar, and then click All Slides.
While a slideshow is playing, move the pointer to make the slideshow controls appear, and then click the Settings button:
To display slides in random order, select “Shuffle slide order.” If you don’t see this option, play the slideshow, move the pointer to make the slideshow controls appear, and then click the Settings button.
Let me know what happens...