If bluetooth audio is generally correctly configured and you know this somehow then something to try out is to set your bluetooth headset as the default sink for pulse audio.
You first identify the device you want to set as the default sink. To do this type:
pacmd list-sinks | grep -i name:
This will list the names of all available audio sinks on your machine. The bluetooth sinks are usually prefixed by "bluez." For example mine is bluez_sink.00_17_43_22_85_86. From the resultant list you need to identify which particular sink name corresponds to your bluetooth device. Once you have the correct name, type:
pacmd set-default-sink bluez_sink.00_17_43_22_85_86.
All applications should now route audio to your bluetooth device.