Using the App:

1) Login to the App
2) Tap on "Settings"
3) Tap on "My Ovvio Account"
4) Tap on "Email & Phone"
5) Edit "Phone number" 6) Verify "Phone number"
7) Tap on "Save changes"

Using the Web:

1) Login to Ovvio
2) Go to "My Ovvio Account" by clicking on your display picture
3) Click on "Personal Information"
4) Edit "Contact Number"
5) Click on "Save"
6) Verify "Contact Number"

Please note that all changes to your phone number must be verified before they are accepted.