How to change your Mac's login passwordYour Mac should have a long, strong password. If it doesn't, you should change it!
The login screen is your computer's main door to your precious, sensitive data. Even if you are using an iMac that never leaves your home office, you should protect that data with a password. It may be inconvenient (though an Apple Watch makes the process quicker), but your personal security is always worth it.
On older versions of OS X, Apple let you use your Apple ID password as your Mac's unlock option, which automatically changed whenever you changed the password on your Apple ID. That said, you don't have to use your Apple ID password to unlock your Mac. In fact, it's not really a good idea.
Ideally, you should use a separate password for every device and service you log into for safety reasons; it's why a good password manager is invaluable. If a nefarious individual or group somehow gets ahold of one of your passwords, it can't be used to access anything else you want to protect.
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How to change your Mac's login password
