For every sign-in you have, it's a good idea to periodically change your password for security purposes.
Sign into your Calendar app. Then, go to the menu in the right-hand corner where your name is located and choose "Settings."
The settings menu will appear across your screen. Select the "Security" option next to "General" on the settings menu.
When you choose the "Security" option, you will see a place that says, "Password." Select where it says "Change Password."
This will allow you to pick and confirm a new password. Don't forget to save it!