I have a Samsung S3 with Android 4.3 and a bluetooth headset. Phone and headset pair and connect without problem. After connecting sound output of the Apps Music (blue note-icon) and VLC work fine with internal speaker and bluetooth. But the sound-output on BT of other Apps like Google Play Music (the one with the yellow headset-icon), Radio FM and other internet-radio-apps I tested does not work. Sometimes a few milliseconds of sound can be heard but that's it. When I adjust the volume with the volume up/down buttons a slider shows alternating the BT icon and the speaker icon. Actually there should be an icon according to the sound-output chosen. After I close the App, the system remains in this state, i.e. BT-output of VLC does not work either, until BT is disabled and re-enabled. It looks to me as if there are two processes working one for BT, one for speaker-output and they are competing with each other. The problem exists for about half a year, before that it was OK. I re-installed the firmware since then and made a factory reset.