Keeping parent/child arrows closed

Hey there!

I've got a lengthy project by month with many parent/child tasks.  I'd like to close the parent task (which generally is the month) so then all the child tasks are hidden.  However, when I do that, it stays open for someone else or it just is open when I go back to it.  Is there a way to keep a parent task arrow with all the child tasks closed for myself and everyone?  For example, when the month of March is completed, I want to "close" March so all the child tasks are hidden and you just see " > March ".

Thank you!