In the HLS format, the Apple recommendation is that you should separate audio and video. This means that when you encode multiple resolutions, you will store the audio only once for all the resolutions and not multiple times and thus save storage and bandwidth.
But JW Player does NOT support when the audio is separated from the video. Each video resolution must have its own audio. To change that settings in MovieStreamer HLS and make sure that all each video has its own audio, click on the HTTP Live Streaming configuration button:
Then in the window that pops up, disable the option "Separate Audio":
This is very important because you won't hear any audio in JW Player if that option is enabled!