By default Unity uses Default-Skybox as a Skybox Material.
Let’s create a Sphere and add a Metallic Material to it.
The sphere in the Scene will look like this:
No matter if the Sphere is surrounded by other objects or an environment, it will always use the same Skybox reflections by default.
And if we change the Skybox Material to other Skybox, the Sphere Reflections will change.
That’s because by default Environment Reflections | Source is set to Skybox.
If reflections on the Metallic objects not changing make sure that Auto Generate at the bottom of the Lighting/Scene tab is Enabled!
Using the cubemap as an environment reflections
Set Source to Custom.
Now we need to apply our custom Cubemap. If you want to learn how to create your own Cubemaps, Read This!
This is a Cubemap I’ve created from a simple Environment.
Let’s add that Environment to the Scene!
Now it looks like the Sphere is really reflecting surroundings.
You can also use Reflection Probe to overwrite Environment Reflections for a specific object/s. I’ve made a video tutorial about Reflection Probes if you are interested!