If you've updated to macOS Catalina, you may encounter a bug in System Preferences, where you're repeatedly asked to update your Apple ID settings, even after following the prompts. This issue leaves a persistent red "1" notification in the Dock, despite your attempts to clear it. Fortunately, there are some effective troubleshooting steps you can follow.
Start with the standard approach: go to System Preferences > Apple ID > Overview and follow the on-screen instructions. Enter your Apple ID and Mac passwords when prompted, and if you have an iPhone or iPad, you may also need to enter its password. If this doesn’t resolve the issue, signing out of iCloud could help.
To sign out of iCloud, go to System Preferences > Apple ID, click Sign Out, and select the option to keep a copy of your data. Restart your Mac, sign back in, and re-enable any sync options like Find My Mac when prompted. This should clear the notification in many cases.
If the issue persists, there might be a corruption in Keychain. Disable Keychain in iCloud settings, go to the Keychain folder in Finder (~/Library/Keychains), and move any randomly named folders to the desktop. Re-enable Keychain and restart your Mac to see if the notification is gone. If this fixes the issue, you can safely delete the Keychain files moved to the desktop.