How to keep functions and stuff closed.

I noticed that when coding on Khan Academy next to Functions and and anything with {} in it there is an arrow you can press hide the code making it neater.

I am assuming that all it does is make it neater.

My question is when I do that and then come back to my code later or copy and paste that code, it opens again. Looking at other peoples codes I often see it closed, how do you keep it closed???

Thank you in advance.