So the Image below shows that under Layers for you to adjust the position in you scene AND in the entire project you need to turn on show all temporary. When you do you can drag the layers in the order you want them to appear. Took me a long time to find that out. The only thing is its the opposite ranking in like photoshop in which the layer on the bottom is shown first and the layer way top is show last. So to answer your question make sure your button is in front so that the other elements are behind it.