spotify -> bluetooth -> car stereo = play ONLY through front 2 speakers

[user-removed]

what i have discovered is that the music from spotify plays through ONLY my front speakers as it would if i were making a phone call.

however, when i play music through the google music application, it will come out through the speakers throughout the entire car including the subwoofer (which it wouldn't before: leading to a very bass lacking sound.) 

playing music from the music app has clarified that the problem is not from the car or phone but from the spotify application. if anyone ahs any kind of tips or tricks to get spotify to play throughout my entire car, i'd gladly appreciate it.

[personanongrata]

i can tell you what spotify support has told me, and will surely tell you, bluetooth is not officially supported.  the old app had a link to take you to android BT settings -- that has been removed in the new app, i presume as an indication that they are not supporting BT (even though their marketing materials claim they do).  BT has never worked well with spotify -- i can occassionally get it to play through my car stereo, but the stars have to be aligned properly, and even then, it's buggy as hell.