You can change the country of your account from Menu > Settings > Account (by selecting your username) > Country. The game will take into consideration the region of your country when assigning the questions. Additionally, in-game questions will be served in the language you entered when starting that game.
Keep in mind that the language of the game interface is associated with the language of your mobile device. In case the game is in another language, we recommend you check the language of your device from Settings.