Double-click the Prefab Asset in the Project window.To open a Prefab Asset and edit it in isolation you can do it in the following ways: You can begin to edit a Prefab in Prefab Mode in several ways. In context: When you edit a Prefab in context, the rest of your current working Scene remains visible, but locked for editing. In isolation: When you edit a Prefab in isolation, Unity hides the rest of your current working Scene, and you only see the GameObjects that relate to the Prefab itself (plus, optionally, a pre-set editing environment - see below). You can edit a Prefab Asset in isolation, or in context. Changes that you make in Prefab Mode affect all instances of that Prefab. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. Think of each unique Scene file as a unique level. More info See in Glossary in your Scene A Scene contains the environments and menus of your game. A GameObject’s functionality is defined by the Components attached to it. Prefab Mode allows you to view and edit the contents of the Prefab Asset separately from any other GameObjects The fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. More info See in Glossary Asset, open it in Prefab Mode. The prefab acts as a template from which you can create new object instances in the scene. To edit a Prefab An asset type that allows you to store a GameObject complete with components and properties.

How to export prefabs into fbx in unity