Enabling duplex printing in HP Printer Driver Settings is straightforward. Begin by opening the document you wish to print and select 'Print' from the file menu. In the print dialog box, locate the 'Printer Properties' or 'Preferences' button. Within this menu, find the option for duplex or two-sided printing. Select it and choose the 'Long Edge' or 'Short Edge' option, depending on your preference. Confirm your selection and click 'Print'.