The Expanded View settings work as follows:
: When this is enabled and you click on a new thought, it will move that thought to the center of the plex. If this is not enabled, when you click on a thought it will make it active, but not move everything so the thought is in the center. Re-Center Collapse on Activate: If this is enabled, when you change to New Expanded View, it will collapse all thoughts so only the current thought is visible. This is only for New Expanded Views, Last Expanded or Saved will still retain the expansion it was saved in. If this is not enabled it will retain all thoughts visible in Normal mode, but now in the expanded mode. The sliders below these two checkboxes are not for Expanded view, they are for Expanded Normal View (yes, it sounds like Expanded mode but it isn't, it's a bit confusing...) - when you click the + button in Normal View to view Grand-Children and Grand-Parents in the plex. If you stay in normal mode, click the + button and start moving the sliders around you should notice the distance between thoughts and visibility of distant thoughts change.