I've answered a number of posts in the Moodle forums from teachers confused by the 'Notify students' option when grading assignments.
(e.g. https://moodle.org/mod/forum/discuss.php?d=322261 )
They are getting frustrated by the way that Moodle does not seem to save the setting. I know that the setting is not supposed to be saved (because it only applies to the grade/feedback that is being submitted at that moment), but maybe some tweaks to the UI would communicate this more clearly?
For example, would the wording 'Notify student about this update' be clearer that the setting only applies to this change (and that it won't be saved)? Or maybe using a checkbox instead of a 'Yes/No' box would more clearly communicate the instantaneous nature of the setting ('Tick here to notify the student')?
There is, I believe, some related confusion about the 'Allow another attempt' option (Maybe a checkbox with 'Tick here to allow another attempt' would be clearer?).