If you mean you change your nickname, in update your details for this forum.
e.g. if you change from Sea princess to (say)sky queen. Your log-on email address is the same, your password will be the same.
In the " my postings folder" you will have listings for both usernames. Of course any reply to any thread started by you, in either name, will be forwarded to your e-mail address. ( if you have selected that option when you started the post.)