Password
Change it under Settings → Security → Change password. Use a long, unique password, and a password manager if you can.
Two-factor authentication
Under Settings → Security you can turn on two-factor authentication using an authenticator app such as 1Password, Authy or Google Authenticator. You scan a QR code, then enter a 6-digit code when you sign in. Recovery codes are shown once while you set it up — save them somewhere safe, because they are how you get back in without the app.
Sessions and devices
Settings → Security also lets you sign out of every session at once, which is worth doing if you have signed in on a device you no longer have.
New device alerts
We email you when your account is signed into from a device we have not seen before. If it was not you, change your password and sign out of all sessions.
Locked out
Repeated failed sign-in attempts temporarily lock sign-in. Wait, or reset your password by email.
Your team
Each person has their own sign-in. Sharing one account makes activity impossible to attribute.