Report problem in Apple app

[deactivated user]

I recently started using Duolingo app on my iPhone 5. Unfortunately, I can seem to find the "report problem" button, since sometimes there are mistakes, that I would like to report to the staff. Is there a button that I don't see, or this option does not exist in the app?

[h.l.o.]

this app has to many bugs

[SmileyVD]

I can click on the flag to report a problem, but it does not let me say which is the problem.