best camera settings for knfb reader on a 4s?

iOS & iPadOS

Good evening,
Does anyone know if there are certain optimal settings that are required to run the knfb reader on a 4s? Everytime I take a picture I always get no text found no matter what, what's the best way to use this app on a 4s? I'm guessing it's probably something I have set up wrong or doing wrong.