You actually can change this for the standard form as well. Go to the MAS_System folder and open the SY_ReportOption.M4T table. Find the form code you want to change and edit the Options String field to show DB_PRINTCOMMENTS$=""F"" instead of ""P"". For the PO form the string would look like this:
5 OptionsString$.. [BT_DESIGNER$="""";DB_PRINTCOMMENTS$=""F"";CB_EXTENDEDITEMDESC$=""N"";DB_PAPERLESSOFFICEOUTPUT$=""1"";BT_EMAIL$="""";LINE1MESSAGE$="""";LINE2MESSAGE$="""";BT_ALIGN$=""""]
As far as I know this works for any of the ""standard"" form and report settings.