I have been changing my whatsapp number by using my son's phone for a short time, but just notice both my son's account and mine has been join together, any suggestion how can i separate up both account now, or how can I restore the setting to the original number.
This happend because of the database stored in your phones storage. Two accounts cant be merged in one. You have been seeing the chats of your son. Just delete the database from the storage and then reinstall Whatsapp with your number.