Hi,
If your monitor is kind of smaller than the app then you'll need to at least run it maximised.
You can set the shortcut to open the app mazimised.
Either using the standard shortcut options - there's a combo box allows you to choose how an app opens.

Or
You can alternatively use a command line switch by appending " -full" without the quotes ( there's a space before the dash ) after the exe in the target.
So your target should look something like:
"C:\.......\GSBPArmyEditor.exe -full"
I've(obviously) substituted dots for the program files or whatever path to the exe.
Come to think of it, there's nothing scaling the content in the army editor like in the scenario editor.
I'll have to think about how best to approach that.
Offhand there are several options
Scale everything - and maybe we end up with stuff looking pretty weird.
Sliders - which'll look clunky.
Make major pieces flow instead of fixed size - which is tricky to get right.