slideshow speed

On an iPhone or iPad:

Tap the display, while the slideshow is playing, then tap "Options" and change the speed using the slider - drag he slider towards the turtle, away from the rabbit.

On a Mac you can create a slideshow project to control the speed. Select the photos, then use the command "File > Create > Slideshow > Apple." To the right of the slideshow pane is a clock icon, where you can adjust the timing.

I can’t change the slideshow speed on an iPhone10. I have about 40 photos in the slideshow. Is the speed adjustment not working because the phone can’t process the file fast enough?