I want to run dual monitors but I can't change mouse protocol from "auto" to "ImPS/2". XF86Config.new is read only...

I log in as the admin (root) but cannot change the damn file. Do I need another edit program other than KWrite?

How do I change the mouse protocol from "auto" to "ImPS/2"?

I'm running Knoppix 3.4

THanks!