If you have two "PIP" at the same time and they overlap each other, then you have two clips on two tracks. In the normal settings the clip on track 1 is overlapped by the clip in track 2. If you want to reverse the situation, simply move the clip on track 1 in track 2 and the clip in track 2 in track 1. See also:
https://help.cyberlink.com/stat/help/powerdirector/21/win/enu/03_06_01_timeline_view.html?anchor=timelineorder&q=order You can also disable track 2 by clicking on the small lock at the left of the track, the lock turns yellow. What you then see is the clip on track 1. (for locking see:
https://help.cyberlink.com/stat/help/powerdirector/21/win/enu/03_06_01_timeline_view.html?anchor=lockingunlockingtracks&q=locking) A third option would be to select (the clip on) track 2, and when you see handles either in the previews screen (they are white balls in the corners, or in the PIP designer (there they are white blocks). and with these handles make the clip smaller so that the clip on track 1 underneath will show.