Can somebody tell me why my iPhone 4 has problems with the SCREEN going EXTRA LARGE FONT so that it is unusable? It is happening more and more, lately and makes the phone unusable while it is happening. Each time, I feel fortunate to get it even to turn off so that it is operable. What happens is that the entire screen enlarges so big that that buttons don't work unless you can manipulate it to get to the off button, and you have to be REAL QUICK and LUCKY. - - - Updated - - - And I have already undated the OS last year, so that has been done already.
I don't know if this is an option for you, but have you considered making an appointment at an Apple Genius bar?
You can change font settings. But if your whole screen is enlarged including fonts and icons; you can do a hard reset. It may save you from this sometime.