Check the box highlighted below and hit OK when done.

If you want to include the confirmation number in the confirmation email, click on File, Business Info, Email tab.  Under each module tab except Petsitting, click the option to "Include confirmation number".

When making an appointment, KC will automatically assign a confirmation number.

Please note:  This function does not check the confirmation box.  KC will automatically assign a number but users still need to tell the system if the appointment is confirmed or not.  You can do this by right-clicking on the appointment and clicking Confirm, or open the appointment and check the Confirm box.

The confirmation number will be included on the confirmation email if you have that option enabled.