> A device like this needs to consider basic safety for measuring and reading simplicity right out of the box because the issue of incorrect high Voltage AC display could end up deadly at some point!
Hm. Hm! If this is an “issue”, then primarily of the operator, not the instrument, I think. ;-)
Since my long gone childhood, I had to do with a lot of different measurement devices, starting from very simple moving coil multimeters up to electronic and autoranging ones. None of them was displaying AC voltage correctly if set to a DC range. (And I would never have even thought of expecting something like that.)
Due to the nature of this application field, it was/is essential for my health and safety that I always know what I’m doing. There is much potential to do something fatally wrong, regardless of the instrument used, so a certain minimum of qualification and awareness is indispensable.
But if this point should still be considered a real “issue”, then I would suggest to change one of two things (or even both):
1.) An appropriate hint should be included in the safety instructions.
2.) There should be no initial default setting like “Current DC” and Voltage DC” for the channels, so the user is forced to explicitly select the intended mode, and the channel displays should show something like “SELECT MODE” instead of digits until he did.
Would that be fool-proof enough? ;-)