I just purchased a GM-30 Plus. The instructions shown above by WRYZ926 appear in Section 6.3 "Dual Watch" of the GM-30 Plus manual. [Note that "single" is sometimes misspelled as "singal."] Nevertheless, when I disable Dual Watch (confirmed by absence of the "D" icon on the LCD), I find neither a Single Mode nor Sync menu item. Either the manual or the radio firmware (or both) appears to be in error on this point.