Talking, but no music

Hi. I'm running my cable box directly into my TV using HDMI (no surround, external speakers, etc.).  On certain stations like Disney Junior, the music all but disappears...however, the talking is loud & clear.  Obviously, I have the cable box -or my TV- set to use surround speakers that I don't own.  How do I set the unit to just send everything -including the music- just to the TV's internal speakers?

I've been all through my TV's settings and nothing fixes it (it's an Insignia).  So, I'm hoping to change a default setting in the cable box...

Thx,

Steve