Usb interface is recording pc sound

I have problems with my USB UR22mk2 interface. I tried to see, how it works on a different PC, but there is the same problem. My interface is recording PC sounds (youtube, music and soo on), at that time, as an input, I marked the 2nd input(i am recording guitar). When i click on “monitor” in my DAW, i get wierd “double” sound like echo, because in my headphones i get 2 exactly the same sounds, one from PC-interface-headphones, and second from PC-interface-DAW-headphones.