I see my joke has missed the mark, it's never as funny when it has to be explained.
As I've previously explained, there is no direct sense of reality, that we can use to understand our place in the world; I think therefore I am, is an assumption, a faith that one has a place in our collective community.
Faith has a bad press, bc we're taught that a fact doesn't require faith, which is true on the face of it; but you can't be sure that your not dreaming this.
"Does it keep changing?"
Yes and no, which circles back to the joke and the point of philosophical thinking...