Each time you press a button a small square will be displayed, move the square in order to fit the current button layout of your Joystick. Go to the "Trigger" tab (for joystick equipped with triggers) ...

But the most important part of the N64 controller isn’t the design or the box it attached to: it was the joystick ... s face button / D-pad / dual-stick / triggers layout with the GameCube ...

As for why anyone would want a six-axis, 17-slider, 128-button joystick, think about this: with this much control, it would be relatively simple to build the MIDI controller to end all MIDI ...