Best viewed in full screen mode on a large screen, should work okay on a tablet. Not designed for a phone.
Control Gallery Display
If both are available a keyboard is recommended.
Use keyboard: Use touch screen:
Hit up/down arrow key to reverse direction. Hit left/right arrow key for manual mode. Hit the spacebar bar to pause/restart. Type ? to see this again. Type 1 - 9 to set number of seconds per image.
Tap ^ button to reverse direction. Swipe left/right for manual mode. Tap the vertical bar to pause/restart. For automatic display, enter number of seconds to display each image: 1 to 9