Apparently the selfie camera (FaceTime HD) can operate in both 30 FPS and 60 FPS modes. I haven’t found a way to change it. Is there one?
To adjust the refresh rate and resolution of the selfie camera, you also have to adjust the video recording options of the main shooter too. Apple does not let you change the settings independently of one another.
Go to: Settings>Camera>Record Video> “1080p at 60FPS” or “1080p at 30FPS”.
You should see the results immediately in the viewfinder.