Hey I figured it out.
Download mx player on whatever and side load it to your stick.
Open up stb and click on a channel. Hit the three bar button on remote and select "media player"
Then click on external player.
A menu should come up asking what external player to use.
Click on mx player and then hit "always".
This fixed the sound problem.
If the external menu doesn't pop up right away unplug your box and try again. Took me about 15 times to figure it out.
Goodluck