Electrician fitted new tyre sensor monitor; now car showing KM and not miles

[tricolore]

It's a 2015 car but new to us. Electrician fitted a new monitor (as the car was continually showing tyre pressures were wrong when they were actually correct). That issue resolved but car now displaying mileage in KM, not miles. He's been here for ages with his computer trying to fix it but no joy so far. Does anyone have any experience/tips/advise please?
TIA

bump

Normally changing between KM / Miles is something easily done in Settings (just as you would change the time etc).
Assuming you have the handbook, is it not in there?

On ours it's something odd like the language settings you need to look at. I've had it before and I ended up going through every setting til I eventually found it. Good luck!

What make/model? It will tell you in the handbook probably if you have it, if not Google and you might find it there.