German names in the i-phone-App get overwritten in english again and again

I’ve two problems, a minor one and a more serious one.
I was asked to split them, so I create two new reports and hope this will work
First the minor one:
In my iNat-Account I’ve marked the preference of german names for the observations.
Nevertheless the plant-names in the i-phone-app I also use are overwritten with the english names again and again. Can I prevend this? When I logout from the app and then login again, the german names are back.