Use the Timeline Selector to select the Timeline instance to view, modify, or preview in the Timeline window. The Timeline Preview button enables or disables previewing the effect that the selected Timeline instance has on your Scene.
To select a Timeline instance, click the Timeline Selector and choose from the list of Timeline instances in the current Scene.
Each menu item displays the name of the Timeline Asset and its associated GameObject in the current Scene. For example, the Timeline Asset named GroundATL that is associated with the Ground GameObject, displays as “GroundATL (Ground).”