Guiding users through updating generated content

I have a page that lets a user generate a comment for students in a class, based on their performance during the year. For the most part, each student will have the same score in all areas, and will not need to be updated.

The refresh button to the right allows the user to regenerate the comment with the same settings, should they not be happy with it. Should the user decide that a student has performed very well in a particular area, then clicking [edit] brings up the following instead.

Once the user has adjusted the values for this student, clicking update will bring him back to the original view, with the graph and comment updated to match the new values, as shown.

(edit: apparently I can't post more than two images at a time).

My question is, what is the most appropriate layout of the page above, both in terms of buttons used, and physical positioning of content and controls, that would make this as intuitive as possible for users to navigate through. The functionality is all there (or can be adjusted to suit if necessary), but more expert eyes than mine in the UX department would be appreciated. Is there a way of minimising the controls used, where the user can intuitively go through the process from start to finish without tooltips or other explanations as to how to do so?