Suppose I accidentally click in the wrong row in the Gradebook (because, say, the "Assignment muted" tags won't go away and they are blocking my view of the gradebook column) and I enter a score (including hitting a return). How can I restore that entry to what it was before I edited (or, at the very least, find out what it was before I edited it)?

On a related note, how can I tell which of my TAs modified a score in the Gradebook (and what it had been before it had been modified in error)?