When adding written comments, the Add to All button is misleading.  When used, there is a small grey-text message that says it will replace existing comments.  This is easily overlooked, and a teacher seeking to have a generic stem comment in addition to student -specific comments could easily overlook this.  The button should be accurately labelled, and there should be an interstitial screen saying "are you sure?" so that the teacher is clear the action will wipe out existing comments.