How set units to kg for seconday user?

I’ve set up my Wyze Scale Ultra and set the units to kg. I’ve invited my wife (several times!!) and she has set up the scale in her app, however there is no Units option under the scale on her app and it is showing weight in lbs. How does she set the units to kg?

EDIT: Looks like this is not just the Scale Ultra having this problem. I found an earlier post for the Scale X that has the same problem so it appears it’s nothing to do with the scale and everything to do with the app AND it has always been an issue. Wyze - please fix this!!

EDIT: Wow this issue has been going on for years across all the scale devices. That’s disappointing and would have made a difference if I’d known about it before I purchased the Ultra as a replacement for my previous scale.
Pity - I was a big fan of Wyze when the company was young but it seems they’ve fallen into the big corporate hole of “we don’t give a shit about our customers”!!