Source code font size preference

I've already poked around the site and in other places online, but please forgive me if this is a common question or one that has already been answered.

I'd like to set the font size controling how my source code is displayed.

I know it can be done for the current windown with ctrl+mouse scroll, but I'd like to set this as a global preference that I can set once and see in every file I open.

Is there a way to do this?

Thanks for your help!