Hi Twan,
I don't know the Roman theme, but I guess this is similar in all themes : if you look at the widget tree of your screen, you will see what webblocks are used to make up the parts if the screen and what layout was used. These webblocks and layouts will typically sit in the Common folder on your interface tree. (or maybe in another module)
Anyway, you can change the layout, or the individual blocks that are part of it there. Changing details of one of the blocks will take effect in all your screens that have that block, changing details in a layout will take effect on the next screens you create based on that layout.
Of course, you can also change the layout of an individual screen.
Is this the kind of thing you are after? If not, can you share some screenshots of you widget tree and your interface common tree.
Dorine