I hope the solution below can solve your problem. :)
The issue was when I connected my laptop to the sony bravia via the HDMI the sound were coming from my laptop and not my TV. After click here and there searching for correct setting, I finally found the solution in the control panel.
What I did back then was, I open the control panel and clicked on "Hardware and Sound" then click on "Sound", then right click the HDMI and choose "set it as default". Apply then finish.
The problem solved for me. Hope it solved for you too!