It seems that users of these apps are saying that the page navigation that pops up gets in the way of reading the bottom of the page. To get rid of the page navigation just tap the screen and it will go away. To bring it back just tap the screen. Also to go to a certain page tap the page number at the bottom of page navigator and type the page number you want to go to. Where ever you close the book app is where it will return when you open book app.