Cannot select People other than myself to head the tree.

Ellen Brumfield

Cannot move the green box to select another person to head the tree. I want to have my parents in as the primary person, so all my siblings can be in the tree. See picture below.

Gordon Collett

You don't select people on the image you posted. It is just a pop up that tells you what you are going to do next. I agree it is a bit confusing. Go ahead and click that blue banner that says Select People, then start selecting all the people you want in the shared group of living people.