reinstalling the game worked.
For the moment my game is in english only and I plan to publish an update with german and italian language support. So after updating the game to new version with multilanguage support, for my users the game will start in their current system language? I mean, because the settings database will not be overwritten by installing an update. So at the first gamestart after apdating, the settings.language will be read from database and because it will be “undefined” it will be set to the current system language, is that correct?