To reshape a single flap, select it with the Subselect Tool and drag the handles on it. The handle at each end is used to adjust the angle, and the middle one is used to adjust the height. Holding down the shift key will constrain the angle to multiples of 15° and the height to multiples of 0.05inch, 0.1cm, or 1mm depends on the units you choose in the Document Settings.
Copy and Paste Flap Shape
The shape of a selected flap can be copied to clipboard by choosing Edit > Copy Flap Shape (Command-C) or click the button in the Inspector. The shape in the clipboard can be pasted to all the selected flaps by choosing Edit > Paste Flap Shape (Command-V) or click the button in the Inspector.
Mirror Flap Shape
If you mirror the shape of a flap, you switch its angles. It can be done by choosing Edit > Mirror Flap Shape (Command-r).
Optimize Flap Shape
In fact, you have no reason to reshape the flaps by hand in most cases because Unfolder can reshape them automatically to eliminate all the problems such as overlap and overflow. Choose Edit > Automate > Optimize Flap Shape or click button on the toolbar and choose Optimize Flap Shape. Then Unfolder will reveal a dialog to let you set a flap height. Unfolder will try to adjust all the flaps to this height if possible. In other words, this height will be reduced if it leads to overlap or overflow. Finally, click the Optimize button.
If only some of the flaps need to be optimized, select them at first.Split and Joint Patches Switch, Add and Remove Flaps