Your book is copyrighted as soon as it is written. Providing a copyright notice or registering your book with the U.S. Copyright Office is not necessary. Editing the book will not change the rights you have in your written words - it just changes the words you have rights in.
For example, when you wrote your first post, the words were automatically copyrighted because they were fixed in a tangible form, created by you, and had a modicum of creativity (well, sort of
). When you edited your post, by either deleting words or adding words or changing punctuation or spelling, the post in its new form was still copyrighted.
Even if you alter your book to the point where you create what is basically a new book based on the content of your old book, you still retain the copyright in the work. No one else can make a "derivative" of your book, except you, without your permission.
(by the way, because of the terms of service of this site, FreeAdvice owns the copyright in your above-posted words, not you)