The changes you make to the configuration of the current drawing are saved on the invisible WD_M block of the drawing. You can save a copy of these settings to the project file. It makes the settings available as defaults for new drawings that you might add later to the project.
AutoCAD Electrical toolset reads both the settings on the WD_M block of the current drawing and a copy of the settings maintained in the current project's .wdp file. Any differences are displayed in a three-column dialog box.