If you select Labels in the layout pane and then Reset Graphic you should be able to shrink all the background columns together, with left-click and drag. Then do much the same with Caps Lock on to reposition the columns.
This is an alternative to "Trying to size the object" that I found even more fiddly, but I believe ought to work (ie select all
• Label from Type your text here, Format, Smaller). This shrinks height and width, which then is difficult to widen again while keeping each column under the right part of the hierarchy. If taking this approach it might be easier to start with Larger (to make it easier to move them apart and widen them) before making them Smaller but this involves too much hit and miss for my liking.