Can't set HDMI audio as default

Hey guys. I recently connected my HDMI output from my LCD to my PC.
I have Nvidia GTS 250. I looked around for some tutorials and solutions to my problem but non of them seem to work since they all say the same thing: set the HDMI as default in my audio settings. I tried but i couldn't do it because it wont let me. I open up Control Panel> Sound and I can't seem to find anything but my SPDIF. When I click on it, the "Set as default" button is not availble. I can't press it. Nore when I right click on it.

I had Nvidia Geforce 8400GS. Nothing. Then I updated to the latest drivers. NOTHING!
So I installed my old GPU, Nvidia GTS 250 and also installed the latest drivers form their website and still nothing!
I tried to remove and reinstall Realtek HD audio drivers and still nothing.

Funny thing: When I right click my SPDIF option I see "test sound" and when I click it I can see the green audio thing goes up at the system tray.

Also... Here's a picture from my device manager:
http://i40.tinypic.com/24evprd.png

Im hopeless I have no idea what to do.... I use Windows 7 64 bit.

please help :)