I have Libre Office 5.0.2.2 running on win 10.
I have set (via Options/Language Settings/Languages) my Locale to English(Australia). I expected this to set the default measurement units to metric but it doesn’t - they remain set to inches.
I can’t find any other place in Options that might serve to set the default measurement unit.
I should add that I had a Libre Office (probably an older version) running on Win 8.1 and I never experienced this problem.