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!

Hi There!!
I am posting here cause I am also having an issue with 5.1 Audio and I don't want to duplicate any post.

Also sorry for my English as this is not my main language.

I am a new Linux user and I have been testing a lot of distros, the one that most likes me was Zorin, and I have been using it for the last 3 months and so far everything its been working fine.

Last weekend I decided to stop using the USB headphones and connect my old 5.1 speaker system, I found that the 5.1 Audio its not working , just 2 speakers sound.

I am using Zorin 15.3
MotherBoard Gigabyte H310M S2H 2.0 (rev. 1.0)
Audio MB info:

  1. Realtek® ALC887 codec
  2. High Definition Audio
  3. 2/4/5.1/7.1-channel
    Appreciate any help!

Please see this first: pulseaudio - how to enable 5.1 sound on ubuntu 20.04 - Ask Ubuntu
and if suggestions there don't help, please see this: The Simple Way to Get 5.1 Surround Sound Audio Working in Ubuntu « Ubuntu Linux Help

Thanks carmar!