You want the entire nozzle assembly as close to the extruder as possible. With the fans off, you'll note that you can raise the "cooling tower" all the way to the plastic extruder housing. This will give you maximum print size.

The added benefit will be you don't have to compress the springs as much, and pro-long the life of the wooden Z-axis bed.

Do not try to adjust the extruder level with filament loaded. For that matter don't even remove the fans.

The jamnut, is know as an hex key.

When you have the Bed-Level, then you can adjust both nozzles to the bed with 2 (two) pieces of paper under the nozzle(s).