We use passwords for everything! We use them to authenticate to our operating systems, email accounts, financial systems, medical records, telephone systems, web services, etc. We are even using passwords to control our televisions and video gaming systems. They are the most common method of digital authentication and have been since the first multi-user computer systems circa 1960. The problem is that because they are used everywhere they are a huge target for attack. The worst problem is that computers are powerful enough now that your passwords can be attacked, and the attackers will be successful.
To change your password go to https://go.byu.edu/changepassword.