How do I get the handles to modify a UI elements size to show up?

As seen here:

How do I get those corner handles to show up, so I can then modify the width/height/location of the element in the Scene.

I've tried clicking, rightclicking, shift clicking, ctrl clicking, alt clicking, ctrl-shift clicking, ctrl alt clicking.....etc Tried changing from blueprint mode to raw mode, to no mode. I keep re-watching the tutorial video on it, and the handles just "show up" for the instructor.

I accidentally made them come up last night, and from that point on any new element I added would have the handles. I have been unable to do it again.

I apologize if this seems like a dumb question, it's just very frustrating not quite knowing how to do something so simple.