If your company uses multiple time clocks, you can set specific buttons on each one individually. You can also set the default event of the time clock here. This way you can easily set up one time clock on your entrance that will always clock an Arrival event and one at your exit that will clock a Departure event.
Go to Clocking points and choose the clocking point which contains the time clock you want to edit. Select the time clock and click on the tab clocking buttons to set the default event and buttons for this specific time clock.