After clearing cache - all my collapsed items (rooms, certain devices that have children) ... all were lost.
I was redoing my settings which have this:
Then I remembered that the the top of the Rooms page i had found a global value for all rooms....
I looked to the top of the page for devices, and lo-and-behold the collapse/expand arrows were on that page! Cool... says I.
I moved to the apps page and saw that the global collapse/expand arrows were there too! I had simply never noticed them there!
This is now my favorite feature of HE!
Clicking it... made my whole app page manageable! Collapsing all the Apps and just opening the one I needed really cleaned up and sped up my work.
Thank you Hubitat!