My Keychain passwords reverted back to old passwords, now I can't access new ones!

Hi duckingaround,

Thanks for contacting Apple Support Communities!

We understand that Keychain displays old passwords rather than the updated passwords on your Mac.

Are you using iCloud Keychain?

Are all newer passwords missing or just some of them?

Do you have a Time Machine backup?

Do you know how long ago the passwords had changed?

If you are using iCloud Keychain and set up a new user account on your Mac then sign into ICloud, are the passwords correct? If you need help to set up a new user account, this resource will guide you: New user or group setup on Mac - Apple Support

"To add a new user or group, choose Apple menu  > System Settings, click Users & Groups  in the sidebar, then click New Account on the right. (You may need to scroll down.)

Note: You may need to enter your password to access the New Account window."

This is also a handy resource to help you to manage your Keychain passwords on your Mac: Manage passwords using keychains on Mac - Apple Support

"Manage passwords using keychains on Mac

macOS uses keychains to help you keep track of and protect the passwords, account numbers, and other confidential information you use every day on your Mac computers and iOS and iPadOS devices.

You can use the Keychain Access app on your Mac to view and manage your keychains. When you use iCloud Keychain, you can keep your passwords and other secure information updated across your devices."

We look forward to your reply.