I can show the desktop in Yosemite using cmd + F3
However I would like to change it to something else. I've done this in the past but can't remember how, and can't find anything online for that matter.
Also when I look under System Preferences I see nothing relating to this action?
Best Answer
System Preferences → Mission Control → Show Desktop. Hold down a modifier key to affect which keys are shown.
You can also see more keyboard shortcut options through System Preferences → Keyboard → Shortcuts → Mission Control → Show Desktop.