If you need to change your listing phone number, simply sign into your account using your email and password you created when you signed up.
Now in your account, click "Edit"
Then click on Contact & Location
Once on Contact & Location screen, you can change your phone number.
Be sure to click Save.
1). Once you hit save your Listing Website automatically updates
2). You do not need to re-post your add via Popular Websites, your phone number is automatically updated.