Veena Nagpal wrote:
Can one change the genre of a book already live on KDP? If yes, how does one do it?
Go to your Bookshelf, mouse over the unintuitive "three dots" in the gray box, and click "Edit Book Details". Select the categories you want, and go through the three screens, saving and publishing, just as you did before.
As C. Gold points out, however, the browse categories that appear on the book's web page may not be the same as the ones you select during publishing. For those, you need to edit your keywords, or simply contact the Zon as described.