Laptop Login has Changed without input from me

Hello George B,
I'm sorry to hear that you're experiencing login issues with your old laptop. It seems like something has happened to the login settings, causing the PIN to be required instead of the BIOS password. Here are a few steps you can try to troubleshoot and resolve the issue:
1. Verify the correct PIN: It's possible that you may have inadvertently mistyped the PIN when setting it up on your old laptop. Try entering the PIN carefully, ensuring that the caps lock is off and that you're using the correct characters.
2. Reset the PIN: If you're unable to remember the correct PIN or it's not accepting the one you set, you can try resetting the PIN. On your old laptop, go to Settings > Accounts > Sign-in options. Under "Windows Hello PIN," click on "I forgot my PIN" and follow the prompts to reset it using your Microsoft account password.
3. Using your Microsoft account password: Since you mentioned that you're able to sign in to your old laptop using the "sign in by other method" option and inputting your Microsoft account password, one alternative solution is to switch from using a PIN to using your Microsoft account password for login. To do this, go to Settings > Accounts > Sign-in options, and under "Windows Hello PIN," click on "Remove" to remove the PIN and revert back to using your Microsoft account password.
4. Check for updates: It's always a good idea to ensure that your old laptop is running the latest Windows updates. Sometimes, updates can fix login-related issues. Go to Settings > Windows Update and check for updates. Install any available updates and restart your laptop if prompted.
If none of the above steps resolve the issue, it's possible that some system settings or configurations have been inadvertently changed. In such cases, you may need to consider performing a system restore to a point before the issue started or reach out to Microsoft Support for further assistance.
I hope this helps, and please let me know if you have any further questions or concerns.