Basic editing for mac: Why can’t I apply the transition to the video?

Currently the transition can be applied to the media on the 1st track (also known as Video track) of the timeline only. If you have dropped the media to the other tracks,such as PIP track. You have to remove them manually. Then go to Media library, drag and drop the media to the 1st track. Lastly drag a transition to the media from transition library.

 apply-to-pip  apply-to-video-track