As of principle, the app uses the language configured for your mobile device.
If you have configured a language on your device for which no translations exist in Untis Mobile, content will be displayed in English by default.
You can configure an additional language for your mobile device, such as German. The app then will use the latter language for content display, assuming it is supported by Untis Mobile (and the mobile device’s primary language is not).
Instructions for language settings can be found here: