That sounds like either a fault with your device or misplaced expectations. On my device the arrow points in approximately the correct orientation. (Plus minus

That sounds like either a fault with your device or misplaced expectations. On my device the arrow points in approximately the correct orientation. (Plus minus ten-ish degrees.) If yours never work even to that level, even when you are away from magnetic sources then probably your device is faulty. (Do make sure you don’t have body worn magnets, or magnets in the phone case/holder of course.) If it works to the same approximation, but you are expecting it to be more accurate then you should choose a different tool for the job.