Thanks stitch101 - you are right. If I'm having trouble with strumming then I need to work on it, and blaming the App is unreasonable. On reflection, what I've learnt from the beginners course is how to make and change chords, and some strumming patterns, but what I haven't learnt is how to put them together for the length of a song and keep in time with drums and bass, while having the vocal melody doing something else at the same time !!!
What the app does is bring a different perspective to learning - I'll stick at it and report back in a few months.
A couple of questions more...
1. will this fourchord app have its own header in the forum?
2. Are there different versions of the app, because on my ipad mini I don't get a metronome and arrows in a toolbar at the top. I can select metronome, which gets rid of those pesky distracting drums, replacing with a helpful metronome, but that is all. I can vary the speed by swiping up or down to the left of the screen.