If I change my UI, How can I save it so when I launch again, it stays?

I dont really fancy the default UI, So I adjusted things around until it looked like what Im used to, Like this


But If I quit, and relaunch, My UI doesnt save, and It reverts to the normal one. How can I save it?

Solved. Go to Window>Save Layout.

Can you undo the saved layout?

Good question. But a better question is why would you want to?
Seriously though I have no idea.