iMovie for iPad Photo Duration

Ok, this is driving me mad. I recently downloaded iMovie for iPad and am attempting to create a video consisting of photos and music. Each photo comes in with a duration of 4s and I would like to make each longer to, say, 6-8s. How? I don't want to spend countless hours clicking 75 photos and dragging them to near the desired length. Surely there's a way; if not, make one because this is a no brainer.