To scroll your multi-page document, swipe up/down. If the document is zoomed in, you can swipe right/left. Vertical and horizontal scroll bars also appear when you begin scrolling.
To zoom in the document, use the stretch gesture: place two fingers on the screen and move them apart.
To zoom out the document, use the pinch gesture: place two fingers on the screen and move them together.
To switch to the mobile view, tap the 
Settings icon Tools icon at the top right corner and enable the 
Mobile View switcher. Now the document corresponds to the width of your screen.