All the existing slides are displayed in the slide list on the left. Tap the necessary slide in the list to display it in the slide editing area on the right.
To scroll the slide list, swipe up/down.
To zoom in a slide, use the stretch gesture: place two fingers on the screen within the slide editing area and move them apart.
To zoom out a slide, use the pinch gesture: place two fingers on the screen within the slide editing area and move them together.
If the presentation is zoomed in, you can scroll a slide swiping up/down and right/left within the slide editing area.