The Settings popup, on the iPad in Landscape mode. Here, you can choose which calendars to include (local, synced, birthdays, et cetera) as well as how far forwards and backwards to include in the overview screen. You select what day of the week the month calendar starts on, and clock mode can be left as your device default, or you can override it to force 12- or 24-hour mode.
You can also set defaults for new events, and toggle sound effects and overlord rules on and off. Finally, there is a link to a Help / About screen.