To amend the Minimum and Maximum values for a specific Class/Event/Course:

From the Booking Screen, single click on the Event Block so that the red border is around the event, as shown below.

Select F7 Action and the following menu will be displayed.

Select Amend Event Minimum & Maximum Values.  The following screen will be displayed

You can now amend the Max and Min People fields and select F3 Accept.  This screen will also allow you to amend the Description of the Event which is displayed on the Booking Screen.