Why is there no audio on my Smart TV while screen mirroring from phone?

[vickisue2]

I have two Samsung Smart TV's. I have a Galaxy S3. I have been using the Screen Mirroring function on both TV's for about a year now. Four days ago I tried to use the Screen Mirroring on the living room TV and there was no sound coming through the TV. I do not have any other audio system attached to the TV. I looked through all the settings on both the phone and TV but could not fix it. I then tried to enable the Screen Mirroring in the bedroom, and again, no audio. I've discovered it's only media apps such as Netflix, Spotify, etc that the sound does not work. Phone ringer, notifications, etc has sound through the TV. I do not have cable or internet so this is the only way I can watch shows, unless I watch them directly on my phone. Can anyone please help me?? I've tried everything I can think of. Thanks!!

 

[SpookDroid]

When you connect to the TV, what does the MEDIA volume slider say? Is it all the way up?

What about apps like YouTube? Or just playing a song in a Music Player (non-streaming preferably)