Don’t worry, in 99.9% of the cases it has to do with one of the following:

– Check the app’s settings located either in the Parents or in the Settings section. If there is a sound on/off button, turn it on.

– Adjust your device’s volume by pressing the volume buttons. If you still can’t hear sounds, your device may be muted. Note that while in mute mode you may still hear some sounds from your device, but some apps may be muted. If you’re using an older iPad or iPhone you can unmute your device using the side switch located next to the volume adjuster. If your side switch is assigned to orientation lock you need to assign it to mute/unmute.