I upgraded to OS X Mountain Lion from Snow Leopard and all of a sudden my scrolls in the browser window (chrome, Firefox etc) have reversed.
I need to scroll up to go down and vice-versa. Is there a way to change the direction ?
You can change this in "System Preferences" -> "Mouse"
This change actually happened from Snow Leopard to Lion with the introduction of Natural Scrolling to match iOS scrolling behavior where the motion is expected to work on the content - not the scroll indicator - as the two move in opposite directions.
The system preference for scroll direction is all-or-nothing and applies to every input device uniformly. With some things, this just doesn't make sense. If you want fine-grained control of which input devices scroll in which way (for example, if you want touchpads to use the "natural" scrolling while having the scroll wheel use traditional scrolling), try ScrollReverser.
You need to go to System Preferences icon on the Dock, then mouse in Hardware category, then scroll direction. The description could be different because I have it in Spanish that I am translating, but you need to un-check it anyway, it worked for me.
In System Preferences, go to Mouse and on the Point & Click tab ensure Scroll direction: natural is disabled
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