Why do I have to turn the trim knob and level controls up all the way do get an acceptable input level?

Newbie here, just trying to figure things out. So far I have plugged in a keyboard, a bass guitar (with active pickup), and a condenser mic (phantom power on) to my AR16. On each chael, I need to tu the level control and the trim up all the way to get an acceptable sound level, and I haven't seen any of the signal/clip indicators tu red.