In the Lighting tab of the Project Panel you find the Lighting settings.
Shadow Quality The slider determines the quality of shadows, in the sense of how high priority the rendering of shadows in the scene is when rendering with Maximum Samples or Maximum Time.
Ground Illumination When Ground Illuminations are on, the rays bounced of the ground will produce indirect lighting.
Self Shadows When Self Shadows are on, the objects in the scene will cast shadows on themselves, otherwise the objects will only cast shadows on the ground.
Ray Bounces Ray bounces are the number of times rays of light are calculated as they bounce around a scene.
Global Illumination Toggle if you want to see indirect ray bounces between objects in the scene.
Global Illumination Bounces When Global illumination is on, Global Illumination Bounces allow you to control the maximum number of times the light is reflected diffusely as it passes through the scene.
Caustics Enable/disable caustics in the scene. See the Refractive Index page for more info about caustics.
The Rendering techniques are optimized for different scenarios.
Product mode is best for scenes where the camera "looks" at the objects from outside.
Interior mode The interior mode is optimized for enclosed spaces.
Interior Mode uses a different and more intelligent approach to samples than the one Product mode uses. The improved approach means that customization of Material Samples only has effect in Product Mode as it is not necessary in Interior Mode.
You can set material samples under the Roughness parameter in most materials and under Advanced in following material types; Translucent and Area Lights.
Save Custom Preset
When you have customized the settings you can save them as your own preset by clicking the icon next to the custom preset drop-down.