Password, two-step verification and devices

Everything here is in User settings › Security.

Two-factor authentication

1. Under Two-factor authentication, click Set up.
2. Scan the QR code with an authenticator app (Google Authenticator, 1Password, Authy…) and type the 6-digit code.
3. Save the 10 recovery codes (copy them or download the .txt). If you lose your phone, a code gets you in: two-step verification is turned off and you set it up again on the new phone. Each code works once.

From then on, signing in asks for the code from the app.

Signed-in devices

Signed-in devices lists where your account is open. Sign out one device, or all the others at once.

Password

Change it under Password. If you've forgotten it, use "Forgot password?" on the sign-in screen.