I had no problems to change the label of "rrpm" and "krrpm"from "Variable" to "Unit" via the menu.
But I remember that from time to time in the past I had a similar problem as the one you describe - changing the label via the menu did not work as the label would immediately snap back to "Variable" as soon as the focus was out of the region.
I don't know what caused that misbehavior.
But changing the label using the keyboard shortcuts always worked OK.
You can use Ctrl+Q to cycle through the seven label-types or you can use Ctrl+U to toggle between "Unit" and "Variable".
According Prime processing disabled regions: No, I don't think that disabled regions are processed to any degree. When you disable a region you still see the state the region was before disabling it.
So if you have a second global definition of the same variable or unit (which Prime no longer allows, unlike real Mathcad) is gets red bordered and when you disable the region the red border persists. I would call it a buggy behaviour or at least something undesirable.
Its similar to evaluating a variable
and after disabling the evaluating region it would still show the former result
I think it would make more sense if all calculation results and error indicators would be deleted when a region is disabled.
On the other hand 'freezing' a result to compare it with a calculation done with changed input values might make sense in some cases, but there sure are other options as to achieve a similar effect.
According persistent error indicator I noticed an even worse effect in 2D plots. A red error border around a plot region would not go away even though the problem causing it was already fixed. A recalc did not solve the problem, saving, closing the sheet and reloading it did. A more convenient solution was to cut and then paste the plot region.
