1. Access the preferences pane.
   
   Keyboard shortcut: Command key (it has a ⌘ symbol) and then the ","
   
   
   
   
2. Click the General, then in the Date/Time format section take notice of Use Local Format checkbox. When checked the Time popup is limited to only 4 predifined formats based on the local settings of your mac.
   
   
   
   When Use Local Format is unchecked the Time popup has 3 different formats.
   
   
   
   
   
   

If you don't see the format you would like, please let us know and we will try to add it in a future update.