Help with buttons

I’m making a family photo album. I’ve imported all the pictures I want. And I’ve turned them into buttons. So when I click the picture it enlarges. But what happens is I can’t click any other ones cause the one button takes up the whole screen. If that makes sense. What I want it to do is be a thumbnail, and when I click it, it enlarges, and when I unclick it, it minimizes. Any help please?