InDesign's Numbering & Section Options dialog box is useful for changing the starting page number of a file, changing page numbering in the middle of a file, changing the page numbering style, and more. The obvious way to access this useful dialog box is to choose Layout > Numbering & Section Options. But there are two sneaky ways to access this dialog box that are easier and faster in many situations.
Sneaky method 1: Double-click on the down-pointing black triangle that appears above the start of a section in the pages panel. If you need to start a new section, select a page in the Pages panel and then right-click or ctrl-click on the page, and choose Numbering & Section Options from the context menu.
Sneaky method 2: If you are working with an InDesign Book file (File > New > Book), double-clicking on the name of an InDesign file in the Book panel opens that InDesign file. But double-clicking on the page number range to the right of the InDesign file name opens the InDesign file, and then automatically opens the Numbering & Section Options dialog for that file.