No sound on bluetooth headphone in Ubuntu 20.04

Yes I had the same problem when I upgraded to 20.04. The bluetooth speaker would connect fine but then not convey the sound from a streaming movie or online radio. It had worked seamlessly before then. So based on this and other posts I read I installed pulse audio. It was still not obvious to me what to do b/c all the "output" devices were configured fine in pulse audio in system settings etc. Turns out I had to go to "Playback" on the top bar menu of pulse audio and then under Firefox (the browser I am using) I had to change the setting to the bluetooth speaker. Hope this helps someone!

So, finally answering my own question.

problem seems that Ubuntu doesn't change all the audio sources to the bluetooth device you can install 'pavucontrol' to change output medium for all applications.

sudo apt-get install pavucontrol

for more details refer this answer.