According to their FAQ:
I changed my phone number, how can I update WhatsApp?
Step 1: update your WhatsApp status with new phone number. Step 2: delete WhatsApp and re-install and register with your new phone number
I already did this several times but instead of recognizing or linking my old account with this number, it is actually creating a new account. The problem I have with this is that I'd lose my paid account (set to expire on 2021) and the new account expires in a one year.
Do I have to input my phone number in international format? How long should I wait until I install the app on the new phone and set up my account? If this keep failing, what should I do? (I already contacted Whatsapp, and boy, what a bad customer service, they haven't replied in a week)