to update a page that uses HTML Editor 2 to HTML Editor 3, you will need to make note of the HTML Editor 2 instance on the page, the Delete it. Go into source code for the page, and make surte that all Traces of the HTML Editor 2 code have been removed.
Then you can add the HTML Editor 3 instance to the page, set the name to use the same name as the HTML Editor 2 instance that you have deleted.