If you just made the change, you might give it a few hours to see if it will correct itself. I don't know if that will happen, but changes don't always happen immediately. Otherwise, you'll need to ask KDP Support to change it for you. Use the Contact US button at the lower right corner of the screen.
Until then, if it's embarrassing for you, go to bit.ly, the link shortening service, and use their link shortener to create an "amzn.to" link for your work. If you sign up with them (for free) you'll have the added benefit of finding out just how many people are clicking your links.