Mesh Attributes Grayed Out in Inspector

Components on imported model files (fbx, max, etc) are always greyed out/inaccessible in the Project view - these will only become active and editable once you create an instance of them by dragging them into your scene view or into the scene's hierarchy window. However, editing the scene version won't alter the component values of the original mesh.

If you need to edit the initial attributes (like the transform component or material names) you'll need to change them either in your external 3d package before exporting to Unity or by making them into prefabs, which will enable the components for editing outside of a scene.

Hope that helps!