I did not mean the unit (that should not matter even if you change it on the fly while modelling) but the scale. If you use the Tape Measure tool to measure a side of the building, what do you get? (I also model in centimetres)
I have 27" and 15" dual screen and sometimes i rotate the big one... When i put it vertical, m'y smooth window appeared in the middle of my 15" screen (where it was not before rotation!)
😍