LR selects the units on the basis of your operating system's regional settings - if you change them in the OS, they'll change in LR too.
My Computer settings are German/German, all and everything German, only Lightroom ignores this and shows height in feet instead of meters.
Which version of Windows or Mac?
Windows 10 64-bit with all Updates, but i do not understand what this has to do with my question. This happens ONLY in Lightroom, the rest of my programs do what they should. By the way, i am not a friend of feet and inches.
LR version/OS version - allows us to provide specific vs generic answers
In your case please check the following:
Go to Windows Control panel and select "Region", then click on the "Additional settings" button
Within that dialog box there is a choice for "Measurement system" if it is "U.S." then change it to "Metric"
A restart of Lightroom is needed after this change.
This changed the GPS measurement units in my installs of Lightroom 2015 on both Win 7 and Win 10.
Some applications like Lightroom as Sarika indicated use the Regional settings of the OS rather than having specific unit/measurement overrides within the program.
That was it. Strange behaviour of Windows. All other Region-Settings were in european units except of measurements. Changed that and WOE, its all OK. Thanks.