Problem with imovie / keynote cannot drag and drop item

macOS and Mac Apps

Hi all,
Recently I came across the following problem which do not know how to resolve, please kindly advice:
1. imovie has a function of droping one picture/video clip onto the timeline video to create overlay video/image. However, for vo+, to work both finder and imovie window has to be opened, how can i ensure both finder and imovie are on the screen? how do I know where is the right place to drop the item?

2. I tried doing presentation with keynote, however when I try to drag the edges of those text boxes, it said it can't be draged, but can only adjust by pressing cursor left or right to have very fine adjustment for every button pressed. how to effectively drag and drop that?