Question about editing a UI in the editor

I have been playing around with the inventory system by Meta, and am attempting to use the editor to change some things on the actual inventory window. since you cannot see the actual inventory window unless you are in preview mode, it makes it difficult to move things around. I figured out you can move elements around while in preview mode, but as soon as i try to alter the size or location of an element it snaps back to the original location when i try to size it, and if i move it where i want it and go out of preview mode and go back, its right back to where it was originally. I figure that if i could do this while not in preview mode it would probably stay, but i cant see it on the screen when not in preview mode.

Obviously i am missing something, is there a way i can do this while not in preview mode?

And yes, i know i can go in to the properties and manually adjust the size and location with coordinates, but i was hoping to use the actual editor to do this.

Went through the hierarchy until I found the nested main inventory box, changed force off to force on and that did the trick.