How do I work with overlaying transparent sprites

Hi I am new to construct 2, and I was wondering how to work with multiple layers of transparent sprites, What I mean is I have about 20 sprites each on its own layer which I have set as PNG and given them a transparent background, But now when I have ( Mouse clicked on the bottom layer sprite) it selects the top sprite.

I figured it was probably the bounding box around the sprite but all I can do is crop which doesn't really solve my problem.

Please help me.

Edit the collision polygon in the image editor.

Thank you