I am not sure I understand the question correctly. You can edit the Personal cache note field at Geocaching.com by clicking it, writing your text and then saving.
The data will be refreshed once per day by Project-GC, and it therefore may take up to ~24 hours until Project-GC notices your changes. Last refresh time can be siin at the Solved mysteries page.
You can not edit it at Project-GC.com, and I don't see why you should. But maybe you are having some thoughts that we haven't had, and you are then of course welcome to present your ideas.