1. I see you have the "High Definition Audio" as the device type. That suggests that you do not have the RealTek sound driver
installed. Instead just the basic function Microsoft/Windows sound driver.
I have RealTek and I have a RealTek HD Audio Manager that will allow SOME (not all) jack assignment changes.
You can only have one default audio playback device and if I understand you correctly, you can't have different devices for different outputs. You can have "Stereo" (2 channel) or 2.1 speaker system that is connected to the Green speaker jack. OR you could have a 5.1 speaker system with the the THREE connections to the PC. But, you can't have one jack for one device or speaker system and another for a different speaker system.