HI @[deleted],
Sounds like you're doing it the right way so I'm not quite sure why you are getting different levels. Are you sure your bus send levels are all the same?

Also make sure they are post fader. This will ensure the volume you set on the fader sent to GTL.

Might be worth checking your individual loop volumes in GTL as well.

To set the audio input via MIDI open the settings and navigate to MIDI. Under the Port heading, tap your midi controller's port to connect it. then scroll down and tap MIDI Bindings then tap the plus button in the lower right corner to add a new MIDI binding. Scroll down until you see the Audio Input function and tap that. Then you will need trigger the button or foot pedal on your controller, GTL should see and register the MIDI command. Then scroll down to the Audio Input option and select the desired input. Click done.