KNFB Reader questions

iOS and iPadOS

I've been using KNFB reader for about 4 years. I've noticed that this app does not work as good as at the beginning. Is there a remedy for that?
Also, how about automatic scanning. When I select that, nothing changes if I rise up my pghone over a printed pagePlease give me some hints.
Greetings. Now I use iPHone SE with the latest iOS 12.2.