There is something wrong in the german translation of the monitor view:
If I set LANG=C, start up qlcplus and add a fixture, I get two options in the 2D view of the monitor regarding the size units: Meters and Feet.
If I use my system language, which is german, I get the units "Messungen" and "Fuß". "Fuß" is okay (although noone would use "feet" as a unit in german speaking countries

It should say "Meter" according to the english translation "meters".
Had this in my mind for years, now, but it never really bothered me - in the 2D-view you always get meters as default - you needn't change anything. Took some time to realize there is another option, and - of course - that it should mean something different...
Long story short: Please change that.

Greets!
Mitsch