Hey, if youre still looking for an answer to this, i figured out that if you change your phone’s language to a country that uses metric units (i.e. i changed mine to English Canada), the default mobvoi watch faces and the google weather app will change their units to metric. Didn’t need a reset at all.
I reset my watch after i read this thread for the first time, so i could change the language to English UK for metric units. That didnt work for me and all the units were still in imperial units. I then tried to change the language on my phone and the units were immediately updated.
I have just purchased a Ticwatch and this is the first thing I noticed watch shows Imperial not Metric and thanks to this Forum I discovered that my smartphone had to be set for EnglishUK . Did this and watch updated immediately to Celcius & Kim’s.