UR44C setup connection

Hi, need help with UR44C connection/setup. Gear: macOS 10.15.7, KRK Rokits6, Yamaha NS10’s (via preamp). I had m-audio interface before, with 2 outputs, so i simply connected both near fields and monitors and could use either sw controls or hw knobs to use them separately, all at once… and so on. With UR44C dunno how. 2 line outputs and 1 main. Tried combinations like neirfields in main, monitors in line, or both to line… there’s always something doesn’t work right… If main output is not used, output knob does not work. Thanks anyone for help.