so i just bought a new sound system. 5.1 (5 speakers+subwoofer). I plugged in everything and wanted to give it a try but i had to notice that only the 2 front speakers are working? i searched in the manual if i have to select between stereo and 5.1 but didnt find anything. I tried it with a dvd and pc, but everytime Only 2 speakers were working. I set the pc settings to 5.1. I hope someone can help me.

Also a little question: is it necessary that the speakers or on the same height level? cause i got the rear ones on 2 different cupboards atm and im not quite sure if thats ok. well i can also care about that when they actually work haha