The "Controls Bar" in Moon+ messed things up

[AZBooks]

I selected, top right 3dots>More Options>Controls bar. Any idea what this is for or what it does? It did not display the typical control bar at the bottom of the screen.

It added about a half inch of blank space at the top and bottom of the page where no text can appear. Also, the pages scroll up and down like a webpage (top to bottom), they no longer do the "real page" flip from left to right.

I manually lowered the top and bottom margins to 20.
...curiosity killed the cat.