HDMI - Sound through Mac not TV

Hi

Watched a movie last night on my Sony TV the picture was excellent.

BUT .. the HDMI sound was output through my Apple Macbook Air .. it was good but not as good as the tv.

Is there a setting somewhere which should allow you to ensure sound comes through the TV speakers?

I know how to do in Windows but new to OSX

Thanks

.. fixed ..

Rebooted and put the HDMI in and then tried again and it worked this time.

No idea why it didn't work before.

I couldn't alter any of the System sound settings but didn't need to in the end.

Maybe my MBA just needed a reboot