My non BMW bike has the kph facility. I don't bother changing it. If the sign says 70 I do 70, it's what the locals seem to be doing most of the time i.e. 60% over the actual limit
I have a similar thing with the digital dashboard on my HP.
I initially assumed it was possible to quickly switch between miles/km per hour but I had to ask the dealer to switch it when I bought it.
I think you can do the same with the GS911 or whatever it is called.