How do I change the language of the Donkey Republic app?

To change the language of the app you need to do it in your phone's settings rather than Donkey Republic app's settings.
iOS: Go to Settings -> General -> Language & Region -> press “Edit” and then drag the preferred language to be on the top of the list.
Android: Go to Settings -> My device -> Language and input -> Language -> Select the preferred language.
The Donkey Republic app is available in Danish, Dutch, English, Finnish, French, German, Hungarian, Icelandic, Spanish, Swedish, Polish and Turkish.