issues with dual monitors on laptop

I am currently using a dell precision m4700 laptop attached to a docking station with an additional monitor attached to the dock. Usually I have the laptop lid closed and the laptop’s monitor disabled and I mainly use the larger additional monitor. I disable the laptops monitor in the KDE control center and make the additional monitor the primary. It works most of the time, but strangely when I start some applications the laptop’s monitor will automatically turn on and become the primary and my additional monitor will become disabled. How can I configure my system so that all applications show up on the additional monitor and won’t use the laptop’s monitor unless told to do so?