On Windows 10 you can change the user PIN as follows:
Press Delete while holding the Ctr + Alt keys.
The following screen will appear, click "Change a password".
Click "Sign-in options" (May be "Other Credentials" on older Windows systems).
Click the smart card icon, to the right under "Sign-in options"
Enter the current user PIN, and then enter the new user PIN and enter it carefully a second time to confirm it. Then click the arrow attached to the confirmation PIN box.
The PIN change should be confirmed.*
*IMPORTANT NOTE for Windows 10 Users: Taglio LLC has become aware of a possible glitch in Windows 10. When the PIVKey software is not installed, instead of a PIN change confirmation, Windows may show an error message stating "The smart card PIN could not be changed. Your credentials could not be verified." This is not the same message you receive if you enter an incorrect PIN, and in some cases we've found that the PIN has indeed successfully changed despite of the presentation of the error message. We recommend you test your PIN if you should receive that message to see if it was successfully changed to the new PIN you entered.
One way to test it, is to Open a Command Window and type certutil -scinfo then press Enter. The command window will display a lot of text, and a dialog box should appear asking for your user PIN. If you enter a correct PIN it will disappear, if you enter an incorrect PIN you will receive an error message.
Enter the new user PIN. If the dialog box disappears and the text continues in the command window, your new user PIN was correctly changed and you can exit out of the command window and any other user PIN windows by clicking the X in the upper right corner of the window or dialog.
If you receive an incorrect PIN error message in the dialog along with a message about the number of tries you have left, you either entered it incorrectly or it may still be the unchanged user PIN. If you run out of retries, the user PIN will have to be unblocked by use of the PIVKey Admin Tools and Admin Key.