As you re-draft your PS, you should be revising it in the light of comments made in the margin. Once you have changed something, if the original comment is still there it can be confusing or misleading when I come to look at your PS again, so please delete the comments as you go along (just click the 'dustbin' icon in the comment to do this).
If you are unsure about whether your revision is good enough, or deals with the comment adequately, you could add your own comment at that point to draw my attention to the issue. For example you might add a comment saying something like: " You suggested I should be more specific about my work placement. I've changed it now. Is this OK?"
That way it will always be clear what stage you are at in the revision process and we can make it more of a dialogue towards making your PS shine 🙂