When you create an override on a prefab by changing a property in the Inspector, normally a blue highlight appears and the property label turns bold. You are also able to right click the property and apply/revert the override. However several properties on the Audio Source component do not do this. When they are changed their styling stays the same and you cannot right click them to apply/revert overrides.

The properties on the Audio Source component that do not properly update when overridden are:

Spatial Blend
Reverb Zone Mix
Spread (under 3D Sound Settings)

1. Install Unity
2. Open the attached project
3. Open MainScene.scene
4. Select the "Music Player" prefab in the hierarchy
5. Look at the Audio Source component in the Inspector
6. All properties contain overrides but not all of them reflect that fact in the Inspector