The Back and Forward can be configured to navigate the active text using several different methods. The buttons are located on the bottom toolbar in the BibleReader.
These two buttons can be configured to navigate in different ways. To select how you would like them to navigate, go to Tools > Scrolling Preferences. "Arrow" is the option that will control these two navigators. You can select to scroll by Line/Verse/Chapter/Book/Screen/History. If you set them to "History" then they will scroll backward/forward through your last ten locations in the BibleReader, acting much like the backward/forward buttons in an internet browser.