There are two methods for doing this.
One is to edit the property in the prefab itself in the project window. This should propagate the changes to all prefabs that have not been overridden.
The other method is to change the property in a single prefab. If you don't "apply" changes, that property will be considered "unique" and will override changes to the prefab. The title of the property will become bold.
If you "apply" the changes, that property will no longer be considered unique and all of the changes will be propagated to all prefabs except for properties that have been over-ridden in any given prefab.
You can "apply" the changes by clicking the "apply" button next to the word Prefab near the top of the Inspector.
Also, this doesn't apply to Transforms. So when you click Apply, all the transform values will go bold (meaning they're custom values now, different from the prefab,) even as the other components of your prefab all stop being bold (indicating that they now match the prefab and will inherit changes from it)