5.1 Audio Playback Issues

I have a problem when it comes to the audio of my system in Zorin OS.
Well, I have connected my Logitech Z906 with both SPDIF and Line Up (3.5mm) and the wierdest thing that it works when i have 3D mode off and it works on the testing section. But when i watch a youtube clip, It turns the front right, front center TO rear right instead. I dont know whats going on with that part and i need assistens for this problem.
The other problem is that i cant get surround with SPDIF only Stereo. The wierdest thing here is that i cant find any Dolby or DTS codecs for this sound card which is a Creative Soundblaster Zx, I have a Creative AE-5 in my hands as well but it doesnt have SPDIF on it so thats why im using the Zx card.
Oh btw, I have installed ALSA Mixer utility to my computer and Pulseeffect.
Please can someone help me with this, it drives my nuts! HELP!