World Outliner: How to force UE to remember which folders were closed?

I have a level with plenty of folders and tons of objects, so whenever I work on it I collapse 90% of them, cause I already finished most of it.

But when I close UE and re-open it again - all my folders are opened again. So I have to waste time over and over again, collapsing unnecessary folders.

How do I force UE to finally remember which folders I collapsed before closing?