In WhatsApp, open Settings (or the three-dot menu on Android) and look for Privacy and Account. Exact labels can differ slightly by phone and app version.
1. Review who can see your details
In Privacy, review Last seen & online, Profile photo, About and Status. Choose Everyone, My contacts, My contacts except…, or Nobody based on what feels right. “My contacts” is a sensible starting point for most people.
2. Turn on two-step verification
Go to Account → Two-step verification and create a PIN you will remember but nobody can guess. Add an email address you control for recovery. This adds protection if someone tries to register your phone number on another device.
3. Check linked devices
Open Linked devices and sign out any browser or computer you no longer use or do not recognise. If something looks unfamiliar, sign out of it and change relevant account security details.
4. Control groups and calls
In Privacy, check Groups so people cannot add you to unwanted groups without permission. Review Silence unknown callers if you are receiving spam calls; it can keep unknown calls out of your ringing list while preserving them in the call log.
5. Be careful with verification codes
Never share the six-digit WhatsApp registration code or your two-step PIN. A friend whose account was taken over may ask for it; call them using a known number before trusting unusual messages.