In the game mario and luigi bowsers inside story how do you save the game?

Okay what I mean by this is how do you save it after you defeat dark Bowser? I have defeated dark Bowser multiple times but every time after i do it takes my to the credits then to the end scene and it restarts and I don't have a chance to save it! its really annoying! how do i stop that? how do i save it after i defeat him!? please help because it is really annoying.In the game mario and luigi bowsers inside story how do you save the game?
You can't. The point of that is so you can replay the boss at any time and pretty much because , hey , it's the end of the game. If they let you save after that , it'd be pointless , what do you plan on doing after defeating the final boss?In the game mario and luigi bowsers inside story how do you save the game?
No offense but FAIL
Ok, had to get that out... um...
Ther are these little rainbow boxes floating in the air that have... i think question marks on them.
But still, did you start n the middle of the story mode or somethig?

EDIT: Oh sorry in that case, you cant. Just kep leveling up to get the last ranks so you can kill Dark Bowser faster.