Not sure what caused this change, but at some point today one of the two monitors I have attached to my Mac Pro started displaying everything (background, pics, etc) larger than the other monitor. It's probably only a 10-20% difference but still annoying as windows aren't fitting correctly on the screen, so I have to drag them to the other screen to stretch them, etc. Can't understand why / how this happened (I'm looking at you wireless mouse!), but it's not zoom function. I can zoom in & out on both screens, although the one with the issue will not zoom to enough to match the correctly functioning monitor display. Guessing this is a simple fix, but googling produced nothing helpful. Any thought welcome.