Refer back to the first picture of this tutorial in order to see how to access each runtime.  When you want to switch runtimes to find something for your scene, you will have to go to the top level again, and double click on whichever runtime you want to open.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi