Hello tomfarney, It sounds like you're experiencing challenges with managing and clearing old passwords and usernames that Windows might be remembering. The good news is that Windows provides ways to manage stored credentials, allowing you to remove outdated or incorrect information to prevent login errors. Below, I'll guide you through the steps to clear these credentials. 
Clearing Stored Passwords and Usernames in Windows
 Using Credential Manager
 Windows includes a built-in tool called Credential Manager to manage saved credentials. Here’s how you can clear stored passwords and usernames: 
- Open Credential Manager
- Press Win + Sto open the search bar.
- Type Credential Managerand press...