This is due to the new PhysicsMaterial feature. Rather than each node having its own "Bounce" property, it's contained in a
PhysicsMaterial resource. This means that you can save and duplicate these physics values easily without having to add them individually. However, Resources are shared between instances so this means that unless you choose "Make Unique" on it, changing a value on one object will change it on all of them.
The tutorial is in need of some clarification to reflect this new behavior.