I add box collider to tank . But box collider does not show up in scene.

I add box collider to tank . But box collider does not show up in scene. I learn from tanks tutorial on unity website I do as tutorial step by step. I `m confused now .

The BoxCollider object is simply an object in the editor for debugging purposes.
If you want to see the collision box, perhaps you should add a MeshRenderer object as well and hand it a material so you can see it in your compiled scene.

When I set tank layer as Default. Box collider show up. But I set tank layer as Players box collider disappear. what is wrong with layer? I do as tutorial