When I put the key in the ignition, the Amundsen starts with the BT audio setting playing music from my phone. However until last week it started playing music from the SD card (I can change it to the SD card and it plays fine). Anyone know why? I want it to play from the SD card always but i cant find a default source setting anywhere.

I seem I remember that mine simply keep in memory the last adopted setting under media.

Yep, mine just goes back to what was last played.