Activate two-step verification in whatsapp 

By default, WhatsApp asks for your number and a one-time pin when changing devices. However, enabling two-step verification means dodgy types can’t get away with accessing your account on a new phone, even if they have your SIM card.

Activate two-step verification in whatsapp

To enable this, you have to visit Settings > Account > Two-step verification. From here, you’ll be prompted to create a six digit pin for whenever you add WhatsApp to a new phone. You’ll also add your email address, in the event you forget your PIN.

One rather massive oversight is that you don’t need to enter a PIN when trying to disable two-step verification from the original device. Odd.