Not in front of the software at the moment but I believe if you are in
Layout mode ([I]F3[/I]), you select the scene template and on of the tabs in the
Object Inspector has an option to [I]set default Framebuffer[/I] for all clips using that scene.
I believe you will need to have the scene object selected in your
Object Manger as well or else you may not see that option. I will try to respond back with a screen cap when I am at my station.
#XPression