Try looking at the sign-out icon with your head not rotated forty-five degrees: it will then appear as an "x."
But, you are right, clicking on that icon does nothing: which is strange.
"What do humans depend on: words ! We're suspended in language: we can never say what's up: or, down. We must communicate experience and ideas, but in ways that do not become ambiguous, and lose objectivity.
For parallels to quantum theory: we must turn to psychology, or to paradoxes thinkers like Buddha and Lao Tzu illuminated, examining reality, as both observer, and actor, in human life's small-scale micro-cosmic drama."