How do I show speed in Km/h?

Hello All,

In my profile on the Connect app I have set the measurement units to metric, however on my watch some data is still shown in imperial measurements.  I notice this most when cycling, where the speed measurement on the watch is well below my speed measured elsewhere, and even by simple "I covered 15 Km in half an hour so typically when I look at my watch I should see a speed of about 30Km/h" but the watch gives a speed of maybe 17 or 18.  The watch doesn't show which units it is using, that would be helpful, but the numbers are right for miles per hour not Km/h.  Do you know how to set speed to Km/h?  Is there perhaps a separate setting for each activity?

My Garmin Connect is installed on iOS.  My Garmin watch is a Vivoactive 5.

Best wishes, Max