The separate monitoring from outputs ?

HI, I don’t understand what mute function, faders, pre and post mix in uTool is good for. For example, When I want to mute the channel no. 1 for monitoring in headphones, it also mutes the sound going out the output 1. The decreasing of volume in fader 1 has a similar effect. I thought the pre or post mix setting will surrmount this problem because the manual scheme includes the separate routing of USB wavs going directly to outputs through a pre mix while the the sound is affceted by faders going to both (headphones and outputs) in post mix. However, I still see the same trouble. The faders make only the decrease of sound on outputs. I don’t understand this because these outputs should be predominantly use for mixers which don’t require any special setings of link or microphone volume level in most cases. Is there any change to solve the separation of mix for both ways ? It seems to be a serious problem for utilization of this equippment for people who need the more complex routing and this architecture is probably good only for karaoke show without the headphone monitoring.