Angry Birds-esque "stars" system

For my Angry Blosics game, I want to know how to make a stars system that, if you beat the level with a certain amount of projectiles left, you gain stars and unlock the next level.
If you have 5 or more projectiles left, you get 3 stars; if you have 3 left, you get 2 stars; if you have 1 left, you get 1 star. The game will save the stars if you beat a level, and the stars will be shown on the button for the level you were last on.
By the way, "Level Button Behavior" and "stars behavior" are actor behaviors.

You already have a code for the stars in your last screenshot, so what's the problem? If you have trouble saving that data for each level, use a list game attribute. https://www.stencyl.com/help/view/lists/
Store in different indexes for each level, and only store your current value if it is greater than the value on the list (of if the list doesn't have that index).

And with that list you can draw the stars wherever you want.