> Logically, setting the default action to edit would not open the WPV, it would open the file within TP for editing.
TP's viewer is also a simple editor, but it's still referred to as 'Viewer'.
The idea (some 21 years ago when TP was first conceived) was that you would use a dedicated external program such as Paintshop to edit your images. Over the years, the viewer has gained many editing features but I guess the wording hasn't changed. And so, 'viewing' and 'viewer' still refer to the internal viewer/editor and 'editing' refers to whatever external program is associated to files of that particular type (in your case, that happens to be WPV which ironically is a viewer rather than an editor).
By default, a double-click or opens the file for viewing, and Shift-Double-Click or Shift-Enter opens it in an external program for editing. This default action can be reversed, as happened on your system.
When you right-click on a file, you can select 'Configure filetype' to change how files of that type will be loaded by TP for viewing (the 'Load using:' value), or which program should be called when you want to edit them ('Edit using:').
