First, all the best for 2014 fellow Amigan's

Whenever I open RTG compatible games or demos on my A4k they always open at about a quarter of the screen size, which is kind of annoying. I've had a search and don't seem to be able to find a way to make them display in more of or all of the screen? is this just the way it is or am I missing something?
Software tried - Adoom , Payback, Bubble heroes - Various Demos.
Running an 060 Amiga 4000 with a CV643D , OS3.9 and CGX4