rogue crotchet rest in enlarged gap between staves that I cannot correct. Why? How to correct?

Your picture doesn't seem to be relevant to the question you are asking (but FWIW I'd bid two clubs, I think :-), but in any case, pictures are seldom useful for investigating problems - attaching the actual score is much more useful.

Most likely, you accidentally dragged the rest away from its true position, so simply clicking it and pressing Ctrl+R to reset it would fix the problem.