From Wix.com

How to Change or Switch your domain URL after you’ve upgraded

It’s easy to change or switch your URL.

Note: this requires you to have upgraded your Wix to a plan that includes using your own domain.

Step 1. Go to My Account and open your Wix creation in the Editor

Go to Wix.com > My Account (Login if you haven’t already)
Rollover the Wix you wish to update your URL info for and click “Edit”.
Your Wix creation will open in a new window.

Step 2. Go to File > Settings (in the Wix editor)

Step 3. Simply type in your preferred URL and hit Apply

IMPORTANT NOTE: Don’t forget to let your domain name registrar know (if you haven’t already).
You’ll find the simple steps to completing this process here.
Please note: It may take up to 3days before your domain changes are updated by your domain registrar.

Still have questions? We’re here to help. Email us: premium@wix.com (it helps to provide your username, the Wix URL and the new & old domain...)