To override materials and shaders on a per layer basis: method 1
 -clicking
            and choosing Assign Material Override from
            the marking menu.
 -clicking
            and choosing Assign Material Override from
            the marking menu.
This creates a material and assignment that will override all shader assignments to objects on the current layer.
To override materials and shaders on a per layer basis: method 2
 -clicking
            on a layer in the Render Layer editor and selecting Overrides
               > Create New Material Override or Assign
               Existing Material Override from the menu that appears.
 -clicking
            on a layer in the Render Layer editor and selecting Overrides
               > Create New Material Override or Assign
               Existing Material Override from the menu that appears.
You do not need to have
               a layer selected to use the context-sensitive menu;   -clicking
               an unselected layer still allows you to override its materials.
 -clicking
               an unselected layer still allows you to override its materials.
            
To override materials and shaders on a per layer basis: method 3


To override layer attributes (render flags) on a per layer basis
 -clicking
            on a layer and choosing Attributes from
            the menu that appears.
 -clicking
            on a layer and choosing Attributes from
            the menu that appears.
            The Member Overrides section of the layer attributes appears.
When a layer override
               is applied, the flag icon for that layer appears in color (red)  .
 .
            
To override render settings, including the renderer, on a per layer basis
 on a
            layer, or select 
                     Window > Rendering Editors > Render Settings.
  on a
            layer, or select 
                     Window > Rendering Editors > Render Settings.
          -click
            on a setting name and choose Create Layer Override from the
            menu that appears.
 -click
            on a setting name and choose Create Layer Override from the
            menu that appears.
            The settings you can override on a per-layer basis include: Render Using, Edge Anti-Aliasing, Size Units, and Resolution Units.
When a render setting
               override is applied, the clapboard icon on the layer appears in
               color (orange)   .
 . 
            
To remove a render flag override
To remove a render setting override
 -click
            on the layer, and select Overrides > Remove
               Render Setting Overrides from the menu that appears.
 -click
            on the layer, and select Overrides > Remove
               Render Setting Overrides from the menu that appears.