Press Console
Radio
Media
Radio
then the App that you wish to have sound come through ex. YouTube, Pandora, Spotify, Internet Eplorer
Check Settings
More Settings
Sounds
Volumes (are those sliders to max volume for media?)
Check the under arm glove compartment if the Aux Jack has a cable plugged in
and the other end of the cable not plugged in to anything.
Here is the video link to fix the issue