automatically based on the system language, if that's the case please make it possible to change the language from the UI, I always use my system language in English as that's my language of preference, however at certain cases it is more convenient for me to read-listen Spanish since that's my mother language, please include a control in the UI to select the language of the books (individually), since I would prefer to have the entire UI in English while at the same time I can choose to read or listen to Spanish in the content