I’ve just tried the margin options as you describe and they don’t seem to work. If I put a single 0 in, the menu moves towards the logo. If I put anything else in the box, the menu moves away from the logo, back to its default position.
10px 10px 10px 10px or even
50px 50px 50px 50px
does not move the menu at all from its default position.
Am I doing something wrong?