Clockwork is doing basically the same thing, the post process volume has a struct that stores all of its settings, the way he is doing it and the way i am doing it are barely different methods that do the exact same thing, follow what he is doing and click on the make post process settings and on the right panel, select what options you want to change. Make sure not to select any options you do not plan on changing because if you do, they will be set to the default value.
In case you still want to use the set members in post process settings node, its as simple as dragging off from the struct variable, and searching for set members, then from there its the same thing as i previously said.