By default, WhatsApp will automatically set your privacy settings to allow any WhatsApp user to view your Read Receipts, last seen, profile photo and status. If you don't share your last seen, you won't be able to see other people's last seen.
Note: There is no way to hide your online status.
To change these settings, simply open WhatsApp > Settings (Swipe down from the top of the screen to access the Settings) > Privacy Settings.
You can set the following options separately for last seen, profile photo and/or status.
Your last seen, profile photo and/or status will be available to all WhatsApp users.
Your last seen, profile photo and/or status will be available to your contacts from your address book only.
Your last seen, profile photo and/or status will not be available to anyone.
If you turn off Read Receipts, your contacts will not see two blue check marks next to messages that they send you. You will also not be able to see your contacts' Read Receipts.
Note: Read Receipts are always sent for group chats, even if you turn off the option in your privacy settings.