The screens are listed in alphabetical order. You'll have to name them appropriately to get them to be in the order you want. I don't want to add a feature to allow them to be ordered because I don't want that to be confusing to anyone. Their order, as listed on the Layout tab, is completely inconsequential to the program, but if you can order them, it will lead to people thinking this will control the order they are displayed.
You can always assign a hotkey to display any particular screen. By default, the "1" key is assigned to the first screen, the "2" key is assigned to the second screen, etc, but you can change that on the Hotkeys tab.