Your COROS watch and the COROS app do not share the same unit settings. You have to configure the setting on the watch and the app separately.
On COROS watches
System > More Settings > Unit > Imperial (feet) | Metric (meters)
On the COROS app
Profile page > Settings > Units > Imperial (feet) | Metric (meters)
Please note, it is not possible to customize different units for different metrics (ex: imperial for distance and metric for elevation).