Whoever designs the "quick disconnect" fittings has a special seat in ****, right next to Satan, himself.
Anything labeled "quick disconnect" is like one of those Chinese finger traps. You can pull, twist, tug, scream, curse, poke, pry and jiggle - only to have it mysteriously fall apart in your hands. You will never remember exactly what you did and you certianly won't be able to easily repeat it when you have to undo that connector again in 3 years. Oh, and that "quick disconnect" will bear no resemblence to any other quick disconnect you will ever encounter - so your brief knowledge will be completely wasted.
That is all.