I have three displays connected to my mac mini. (I have used Arrangement to make sure they are connected correctly left to right, so mouse movement works correctly.) The leftmost is the primary with the dock. However, the middle display is call "Display 3" and the rigtmost is "Display 2". Even if I swap the cables, it still stays the same, so OSX must remember the displayid. This is a problem because Desktop numbering (in Spaces) are out of sequence rigt to left across the displays. It is also confusing that when you assign an app to a display, you have to remember that 3 is the middle display. I know I could just physically swap display 2 and 3, but can this be solved through macOS Display settings? :-)
Any suggestion on how one can reassign the numbering of the displays?
System Preferences... > Displays > Arrangement
does not work for you? – IconDaemon May 17 '19 at 11:02