Why can't I modify the sky_sphere via blueprints?

I see what everyone is talking about…my question is how do I change these via a trigger box in blueprints?? When I try to change the material in blueprints the material doesn’t show up in the material network. And If I try to change the variables nothing happens.
Im confused.

I FULLY understand that I can altar all of this. But I want it to change when I tell it to. Via the sky_sphere BP. How can I get the noding to work???