There are tutorial videos here: https://zubersoft.com/mobilesheets/tutorials/
This tutorial discusses the different display modes, and the one you want is the vertical scrolling display mode: https://www.youtube.com/watch?v=V_8GXnlNfm0
First watch around 0:30 until you can see how to change the display mode. The vertical scrolling display mode is discussed at 5:07. If you switch to that display mode, then you can scroll vertically like you are expecting. If you use the automatic scrolling with the single page display mode like you are doing now, it will only turn pages as the page can't be scrolled. If you rotate to landscape, then it will both scroll and turn pages.
Mike
This tutorial discusses the different display modes, and the one you want is the vertical scrolling display mode: https://www.youtube.com/watch?v=V_8GXnlNfm0
First watch around 0:30 until you can see how to change the display mode. The vertical scrolling display mode is discussed at 5:07. If you switch to that display mode, then you can scroll vertically like you are expecting. If you use the automatic scrolling with the single page display mode like you are doing now, it will only turn pages as the page can't be scrolled. If you rotate to landscape, then it will both scroll and turn pages.
Mike