If you place the cursor over the right hand edge of the still and see a
double headed arrow you can drag the picture out or in to vary the time.
Expanding the time line can make it easier to get more accurate. Otheriwse
you can remove it from the timeline, change the still duration to whatever
time you want and tehn drop it back on the timeline.
More info here if you need it. http://www.myvideoproblems.com/Tutorials/MovieMaker/ChangeDurationStillPicture.htm
