Hello,
I want to change the language of the whole app on different screens with one button click and to save these settings in a tinydb. How can I do this please? Thank you.
Martina
Here is one way. This is called 'localization' .
Here is a simple example . Sorry, the old link is missing some links. Here are the missing parts:
Localization.aia (7.6 KB)
There are other ways. This one requires storing in your app the complete texts in each language you want to be able to use. You might use Taifun’s tools extension to discover the Android device current language 
and select the language file you want based on the language codes provided by his tool.
The above example is simple; what you hope to do is complex and depends on how you presently save the existing text and where you save the alternate text.
Thank you very much. It is not so easy to understand, but I will have a look at your aia. Thank you!
You can use Any components. All that contain text. Buttons, labels, check boxes, etc. In a loop, read their text, then use the translator to translate and save the original and translated text to the csv table. You can review the tables and possibly correct the translations. Then modify the code so that it doesn't translate but fetches data from the table.