Save text location during app switching

I open the split screen, move the divider up so that the bottom part of the screen takes all iPad's screen. I open there a commentary on Matthew 18:21–35 in "Feasting On The Word", Year A, then I scroll down to the Exegetical Perspective section. 
Then I swipe up from the bottom of the screen to switch from Accordance to the home screen and immediately switch back to Accordance by tapping its icon; the app has already jumped back to the beginning of the Matthew 18:21–35 commentary. Why? Why can't it stay exactly where it was before switching to another app?