On the Transition track of the timeline, do one of the following:
To increase the transition duration, drag the beginning of the transition towards the beginning of the timeline.
To decrease the transition duration, drag the beginning of the transition towards the end of the timeline.
Note
To view the Transition track of the timeline, expand the Video track. The original default time the transition appears is determined by the value for the Transition duration box on the Advanced tab of the Options dialog box.