To change the units in the phone App, you must do it first on Desktop. The change will be applied automatically in the phone App.
For every layers ( Wind, Rain, Clouds....) you can change the units in the colour scale as shown here:


You can change also some units in Meteogram:


In weather diagram,
1 Select Meteogram
2 Click to change unit of cloud base
3 Other units can be changed too : ºC, kt, hPa, mm
By this way it is possible to modified directly these units in the phone App