I have a four digit PIN to start Windows. How can I change this number?

To change your PIN in Windows 10, you may follow the steps below:

1. Open Settings (keyboard shortcut: Windows + I) > Accounts > Sign-in options.
2. Click the Change button under PIN.
3. Enter your current PIN; then, enter and confirm the new PIN underneath.
4. Tap I forgot my PIN.
5. Enter your Microsoft account password; then, set up the new Pin.