You can edit your phone number in your ad by:
1. Click on "My Account" and then "My Ads".
2. You'll see many options below your ad, including "Edit" option.
3. Click on "Edit" option and add your new phone number.
4. To save your edits, click on "Save and Publish Ad" below the ad details.
- so that the phone number you modified will only appear in your ad that you've modified.
If you want to change your phone number in your account and all your ads, you can edit it by:
1. Click on "My Account" and then "Edit My Account".
2. You will see the registered phone number in the account, you can edit it by pressing "Change" next to the box.
3. Enter your new phone number and press "Save" to save your changes.