Realtek HD audio manager

[ntrmn]

I have Realtek HD audio manager for 5.1 suround sound speakers. When I play music from online, pandora.com, I only get music from my front side speakers and sub, but if the music is saved on my computer all the speakers play.

Is it called upmixing, to get all the speakers to play? Can I get all the speakers to play all the time?

Thanks