How can I make Signal, WhatsApp and Telegram more private?

These three apps look similar but protect you very differently by default. "End-to-end encrypted" means only you and the person you are talking to can read a message - not the company, not anyone who intercepts it. Knowing which app gives you that, and where the gaps are, gets you most of the way to private messaging.

What each one protects by default

Signal

Everything is end-to-end encrypted - messages, calls, the lot - and Signal is built to collect almost no information about who you talk to. It is the benchmark other apps are measured against.

Your messages and calls are end-to-end encrypted by default, which is genuinely strong. Two things to know: it is owned by Meta and still collects metadata (who you message and when, even if not what you say), and your chat backup to iCloud or Google Drive is not encrypted unless you switch on encrypted backups.

This is the big misconception. Ordinary Telegram chats are not end-to-end encrypted - they are stored on Telegram's servers, which can technically read them. Only "Secret Chats", which you start manually and one-to-one, are end-to-end encrypted. Groups and channels never are. Treat a normal Telegram chat as convenient, not private.

Settings worth changing

In any of them

Turn on disappearing messages for sensitive conversations.
Lock the app itself with a PIN or biometrics.
Review who can see your profile photo, "last seen" and status, and turn off read receipts if you would rather.

Signal

Set a Signal PIN and turn on registration lock - this stops someone re-registering your number on their own phone, which doubles as SIM-swap protection.
Use a username so you can share it instead of your phone number.

Turn on end-to-end encrypted backups, or your chat history sits unprotected in the cloud.
Enable two-step verification (a PIN) to stop your number being hijacked.
Silence unknown callers and limit who sees your profile.

Use a Secret Chat for anything sensitive - ordinary chats are not end-to-end encrypted.
Turn on two-step verification.
Set who can find you by phone number, and use a username so you need not share your number at all.

If you only do one thing

For anything that truly must stay private, use Signal - or a WhatsApp chat with encrypted backups switched on. And remember that on Telegram, only a Secret Chat is end-to-end encrypted.