Ask Max: My Apple Mouse Won't Scroll Up - Only Down!
This is the second apple mouse I have bought for my Mac. The problem with both of them is they will not scroll down, just up using the little scrolling button on top. What gives?
Thanks for any help you might offer. The old one was wireless this newer one is USB - I disconnected it and plugged it back in but nothing helped.
Since you're specifically talking about an older mouse, it sounds like you might have a dirty scroll ball issue. There is not likely a problem with your computer or the mouse hardware. You just need to clean the dirt out of the scroll sensor. This is so common that Apple made a demo video on how best to clean your mouse.
If you're using more recent technolgy, like the Magic Mouse or Magic Trackpad, you might be experiencing directional scrolling issues as well. The defaul for both devices is what Apple calls "natural" scrolling. The page moves in the same direction as your fingers. If you use the scroll gesture (two fingers) in an upward motion, the page actually scrolls down. Personally, I find this backwards, so I go into System Preferences, click on mouse or trackpad, and uncheck the "natual" movement. This way when you pull your fingers down, the page scrolls down as well.
It really comes down to personal preference. Apple has a support document that walks you through the steps.