A PIN is a set of numbers, or a combination of letters and numbers, that you choose yourself. Using a PIN is a quick, secure way to sign in to your Windows 10 device. Your PIN is securely stored on your device.
To reset a PIN when you're already signed in:
Make sure you're connected to the internet.
Select Start > Settings > Accounts > Sign-in options.
Select Windows Hello PIN > I forgot my PIN and then follow the instructions.
The PIN you use to access your device is different from your Microsoft account password. If you need to reset your Microsoft account password, go to account.microsoft.com, select Sign in and follow the instructions. Next, select Your info > Profile > Change your password > Change and then follow the instructions. If you're worried that someone has unauthorized access to your account, see Recover your Microsoft account and Security info & verification codes.