Go to your Writing Studio dashboard and click on the gear symbol at the top corner of your book to be redirected to the title page. You can also access the title information page by selecting your book in the Library.
You can change the details of the title page from here, and it will automatically update on the print version of your book.
If you also want to change the description, you can do so on the title page. The book description must be more than 150 characters, and less than 1000 characters. If the book description does not meet this criterion, it will show an error and will not save.
NOTE: Text entered in the description on this page does not automatically show anywhere else. You'll be able to enter a summary of any length on your publisher's website, and you can put whatever you want on the back of your printed book. The description here is really for your purposes only.
Happy Writing!