When you create your account with us we will automatically generate a unique URL for you to share with your gift givers. If you would like to change it, you can only do so through our website, not the app. Go to Settings > Registry Info. Scroll down until you see Registry URL.
Remove your old URL and then type in your new one.
Scroll down to the bottom of the page and hit "Save".
If your changes have saved, you will get this message:
If you do not get this message then the URL you have chosen is already in use. You'll want to go back and edit it again until you receive this message.