If your keychain password is different from your username password on your Mac, change your keychain password to match your user password by following the steps here:
If you need to update your keychain password on Mac - Apple Support
If your keychain password is the same as the macOS user account, changing the user password will also change your keychain password:
Change or reset the password of a macOS user account - Apple Support
Specifically, follow these steps:
Change your password
If you know your password and can use it to log in to your account, you can change your password in Users & Groups preferences:
Choose System Preferences from the Apple menu, then click Users & Groups.
Select your user name from the list of users.
Click the Change Password button, then follow the onscreen instructions.
If you're still encountering an issue after trying the steps above, you can manually reset your keychain to create a new login keychain:
Create a new login keychain, if necessary
After resetting your password and logging back into your account, you might see an alert that the system was unable to unlock your login keychain. This is expected because the passwords for your user account and login keychain no longer match. Just click the Create New Keychain button in the alert.
If you didn't see an alert about your login keychain, or you see other messages asking for your old password, reset your keychain manually:
Open Keychain Access, which is in the Utilities folder of your Applications folder.
Choose Preferences from the Keychain Access menu, then click the Reset My Default Keychain button in the preferences window. After you enter your new password, Keychain Access creates an empty login keychain with no password. Click OK to confirm.
If you don't see a Reset My Default keychain button, close the preferences window and select the “login” keychain from the left side of the Keychain Access window. Press the Delete key, then click Delete References.
Choose Log Out from the Apple menu to return to the login screen.
Log in to your account using your new password. Your account password and login keychain password now match again.