You are right, but how? There's nothing about how to do it, not even in the manuals.
And now this triggered me another question, what do they exactly mean by "factory setting" if it does not guarantee the correct temperature? Is that what they saying? Then they store the settings and then calibrate the unit, and the accurate settings are not saved? or they talking about the reverse offset I apply to go back to original temperature reading? If this is the case then it's not a linear thing, and the unit requires calibration again. Now I'm more confused.