I am using appointments + and am trying to schedule

I am using appointments + and am trying to schedule appointments every 30 minutes, and the appointment lasts 1 hour. For example, allow someone a choice between 9:00, 9:30, or 10:00 to schedule a 1hr appointment. Under settings general tab I have the time based set for 30 minutes, and under services tab duration is set for 60 minutes, but the calendar only allows them to book on the hour? Any help would greatly be appreciated. Also I have in general settings the appointments lower limit set for 2 hours, but the calendar does not let them book for another 10 hours, how do I get it set so they can book 2 hours from now if they want? Thanks