Using the NVR's Local Interface for when you are physically in front of the NVR with a mouse and monitor attached. 

1. Log in: Access the main menu by entering the current admin password. The default password is often 1234 (if it hasn't been changed before).
2. Navigate: Go to Menu > Device Management > General Settings or a similar Account/User management section (Can vary depending on firmware).
3. Select User: Choose the user account (typically "admin") whose password you want to change, and press edit.
4. Enter New Password: Look for an option to "Change Password" or "New Admin Password".
5. Input Details: Enter the Old Password, then the New Password, and Confirm the new password using the on-screen virtual keyboard or a connected physical keyboard.
6. Apply Changes: Click Apply or OK to save the new password. 

Important: Please be sure to securely record the new password. There is no way to recover or reset the password if it is lost and not documented.