How to change or update Whatsapp phone number?

If you have acquired a new mobile number and you would like to update your Whatsapp number with it, follow the steps below. 

1. Open Whatsapp > press menu
2. Tap Settings > Account
3. Tap Change number
4. Tap Next

5. Enter old phone number  and the new phone number > done

By changing Whatsapp phone number this way, your account info, groups and settings are migrated to the new number.