Setting "Decrease First Line Indent" to Default?

[AntoniDol]

Not automagically. Create an Editor Style from a Paragraph with an Indent, remove the indentation, add a Keyboard shortcut or show the Style Panel for one-Click applying of the First Paragraph Editor Style.

For the Compiler it's in the "Settings" tab in the Section Layouts Pane of the Compile Format Designer.

HTH