im not sure what you're talking about?

you mean the All Grouped movement setting? Im pretty sure there is no way to set it to default, but when you build a fleet, just remember to set it then... i cant think of too many examples where you would want to change that setting really, unless you are retreating, in which case you press the retreat button and it automatically overrides the group jump setting

if you are talking about the visual formation when ships are lined up all pretty on top of each other etc etc, then i have no idea how to even do that normally, let alone default... sometimes the ships line up sometimes they dont, its kinda annoying but oh well