Calibrating the DSO Nano v2 - Help

ok, i have had a few days to mess around with this device… And it is a good little scope.

I have a quesiton on calibrating the v2, I know the basics of having the trace centered, etc…
But, with that being said, if I go to “ME” and look at the data, I am getting variable
numbers in the vpp / Vmin, Vmax & Vavg. How does one go about getting those to ZERO?
Would that not be accurate?

It also seems that when I messed around with the cal off and cal gain a little (not having a clue what I was doing)
The trace line that HAD a little noise was completely flat. ?

Also, once I shut the unit off and turn it back on, I have to move the V pos back to center
Is there a way to save my setup?

Just looking to make it more accurate…

Thanks…

In real life, nothing is really exact (such as power supply voltage) or precisely square (such as the test signal) even when viewed on the most expensive devices money can buy. That is if we look close enough. Some of the “impurities” may come from the test instrument, but may equally well be part of the signal we measure. Understanding the cause and nature of the impurity is part of learning to operate and use your scope. We don’t want to eliminate these parts of the waveform as it may very well be exactly what we need a scope to reveal.