To adjust your speaking volume:
Use the speaking volume dial on the top of the amplifier (see below) to adjust how loud you sound to your caller.
If you sound too loud, move the TX Level switch (see below) from the high to the low setting (and vice versa).
To adjust your listening volume:
Use the listen dial on the top of the amplifier (see below).
If the volume still isn't adequate, make the necessary adjustments using the volume controls on your headset.