Shift movie horizontally for side by side

I have two videos where the action appears on the left side of the frame. Using iMovie version 10.0.9, I use the side-by-side overlay. The bottom (right) video is overlapped by the top video so the action is not seen. How can I shift the bottom video to the right so that the action appears on the right side of the side-by-side? Can I edit the right side video 1st so the action has been shifted to the right side of the frame?