HTPC 5.1 trouble

[zerocool459]

OK there my problem

I made a HTPC with asrock h110-m dgs and g4400 (i link my panasonic 55inch 1080p (2016) i can find the model if needed .. with a HDMI cable.. but i cant get more than 2 channel out of my hdmi

i know my mobo was 7.1 
so now i cant get my full 7.1 out my receiver (no my receiver didnt have hdmi in)

and my tv was link with optical cable to my receiver (its work if I put my usb drive right in the tv and play surround movie) .. my receiver show up 7.1 channel and dolby or dts depend of the movie codec 

so i dont understand why i can push more than stereo out of my hdmi option in windows 10
 

[Electronics Wizardy]

what is the source audio? Try playing a source with 5.1 like a dvd.

[zerocool459]

like AC3 

[zerocool459]

the same movie push by usb right on tv work but not by hdmi from htpc