How to switch horizontal and vertical scrolling directions I would like to know how to switch horizontal and vertical scrolling in OS X 10.9, i.e. when rolling the ball to the left to make the screen go down, and when rolling right to make the screen go up.

Question is not how to switch horizontal/vertical direction!
Question is how to switch axes x and y.

Does anyone know how to do that? Thanks in advance!
System Preferences > Mouse

Scroll direction check box will be at the top of that window.