How do we not let go of the accelerator without changing the controller setup from the default?? simple my good friend
How I like to explain this is in biological terms, if you look at your thumb its comprised of three segments:
The metacarpal bone which is the part of the thumb connected to your hand
First Phalanx (segment in the middle of the thumb)
Second Phalanx (Tip of the thumb)
The best way to hit the square fire button without letting off the thrust goes like this. Having your Second Phalanx on the accelerator move your thumb across the X button until the Second Phalanx meets the Square button and the X button is being held down by the actual joint between the Second Phalanx and your First Phalanx.
In short: Move the tip of your thumb over to the Square Button but keep your thumb pressing down on the accelerator until the joint presses down on it. You should now be able to fire without letting up on the thrust
I love my A level Biology ^_^