You can quickly edit single clocks or groups of clocks.
Choose View > Clocks.
Double-click the clock in the list or select it and choose Edit Clock from the Action pop-up menu (looks like a gear) at the bottom of the list.
Change the clock as needed and click OK.
World Clock Deluxe lets you also change the format or label for multiple clocks at once.
Choose View > Clocks.
Select the clocks and choose Batch Change from the Action pop-up menu at the bottom of the list.
To select clocks that are next to each other (contiguous) in the list, press the Shift key and then click the first and last clock; to select clocks that are not next to each other in the list, press the Command key and then click each clock.
To show seconds in all clocks, select the Seconds checkbox. To hide seconds in all clocks, deselect the Seconds checkbox. If some of the selected clocks show seconds and some don't and you want to keep the current settings, leave the dash in the Seconds checkbox (if you have clicked the checkbox by mistake, click it again until the dash reappears).
Proceed in the same way with the other clock format options (Weekday, Date, Date change, Local time offset, UTC offset, Time zone, and City/time zone/text). The "Time zone" checkbox lets you show or hide a city's time zone (e.g. EST or EDT for New York).
To apply the same weekday, date, or time format to all clocks, choose it from the "Weekday format", "Date format", or "Time format" pop-up menu. If the selected clocks have different weekday, date, or time formats and you want to keep the current settings, leave the empty menu item.
To assign the same label to all clocks, choose it from the Labels pop-up menu. To remove all labels, choose None. If the selected clocks have different labels and you want to keep the current settings, leave the empty menu item.
Click OK close the dialog and change the selected clocks.