How to adjust direct monitoring level mix in UR44?

I see the reverb send but I can’t find where I can adjust how loud singer’s voice goes back into headphones (if they want to hear themselves louder/quieter).

Please?

With the channel strip fader either in Cubase or in dspMixFx if you are using another DaW. In Cubase, you select where the channel strip is in the signal flow. If you select Monitor, the strip is after the signal is sent to the DaW, so the DaW recorded signal is not affected but the signal is then sent to the UR Mix bus and the outputs.