You can turn the game and interface sounds on / off separately.
- If you want to turn off game sounds, just tap on any game you want and start it. On the top left side, you will find a "II" symbol, which will stop the game. Once you tap on it, a menu will appear (Restart, Help etc.). At the very bottom you'll find the option to turn the sound on and off.
- If you want to turn off interface sounds as well, just go to the Account & Settings menu (go to the sidebar of the app, tap on your name / the Peak logo at the top), and scroll down. You will find the option to turn the interface sounds on and off.