Lefty loosey, righty tighty. Or, clockwise-close.
Your M&S gauge may not be any more accurate than the old compressor, y'know. What you need to do is not get fixated with numbers, but rather use them as a baseline and stay with one specific measuring device so at least you're consistent. For example, your Dad's compressor one might be reading 10psi over, but it doesn't really matter. Just make adjustments based on that, so if it's too high then lower the pressures but stick to that one device.