Media Audio... choice reverts to "Let App Decide"

I've been working on adding an aux in to my car stereo which is working "perfectly" now.  The only issue was that the phone would switch from outputting music to the headset to outputting to the phone speaker between songs and when I lowered the car stereo's volume too low while the phone was paused. Previously I would simply break and reconnect the ground wire and audio would start coming through the headset jack again.  I am now trying to use SoundAbout to keep the audio being sent to the headset jack.

The problem I'm having is that for "Media audio....", the choice keeps reverting to "Let App Decide".  I set it for "Wired Headphones" but still between songs, the audio switches to the phone speakers.  I then go back and look at the settings for "Media audio...." and it no longer says "Wired Headphones" but has now reverted to "Let App Decide".

How can I keep this from switching?  I'm running the trial version.
Thanks!