Most openers have similar adjustments. Opening travel limit, closing travel limit, opening force limit and closing force limit. You need to adjust the closing travel limit slightly to be sure the door is closed tightly against the seal. If you go too far, the closing force limit will tell the door to open.
I never really thought the opening force limit was too important until one day my door froze to the floor and I didn't know it. When I hit the button to open the door, the door didn't want to be opened and the opener proceeded to destroy the top panel. Lesson learned, about 800 bucks worth. Check the book and be sure ALL of the adjustments are set properly.