Thanks for the reply!
My receiver has dolby pro logic ii mode but this mode is only available for stereo source.
My pc is connected to receiver via hdmi so it is connected through pcm (which i think is sending 5.1 signal), so it cannot use the dolby prologic mode. It can use the dolby prologic...
My setting is
PC with gtx 980ti connected to LG receiver with hdmi then connected with 5.1 surround system
Audio settings in pc is set to 5.1 surround system
When I play games that support 5.1, it works fine.
When I play youtube music, only two front speakers and subwoofer works but rear...