After installing Ubuntu 12.10, the first thing I wanted to do, was to disable reverse scrolling – you scroll down and it scrolls up! This is also called natural scrolling by Apple. Don’t know what is natural about it :) but may be natural for Apple users.

Open the terminal and edit this file using any editor and edit the .Xmodmap in your home directory for example:

 gedit .Xmodmap

Here you would seet his:

pointer = 1 2 3 5 4  6 7 8 9 10 11 12

You would note that in the sequence of numbers 5 and 4 are interchanged. Change it back to the sequence..

pointer = 1 2 3 4 5 6 7 8 9 10 11 12

Now you are done, logging out and in should do the job.

If you have Ubuntu Tweak installed. Just go to Tweaks-Miscellaneous and you would see an option to toggle Natural Scrolling on/off.