After months of trying every single possibility I finally found the solution! you just need to DISABLE the Realtek High Definition Audio in the Device Manager !!! makes sense doesn't it? this thing wasn't allowing the Intel(R) display Audio, which is the audio through HDMI, to take over. once you disable this, go back to playback devices,select the Intel(R) display audio (which is probably the only in th elist now) and press configure in the bottom left, and surprise surprise! you have all the possible channel you dreamt of, from stereo to 7.1 ! chose the want you want and voila! enjoy.