I am trying to make a picture in picture in FCPX that is round, but I can only manage it square, does anybody know how to do this? Also when I add a transition to my pip it also affects my main clip, how can I add it only to the pip?
Use Element shapes shared in Compound with whatever video/images you want as PIP. Make sure Shape (Ellipse) is on top in Compound and apply Stencil Luma as Compositing.
Place above Primary and scale/position to your liking.