Tools; Admin; Change Password - D-Link DSM-600 User Manual

Section  - Configuration
User Name: The user name is set to admin. You cannot
change the user name.
Password:
Enter the old password.
Enter your new password.
New Password:
Comfirm Enter your new password again.
Password:
Apply: Click Apply to save your new password.
D-Link DSM-600 User Manual

Tools

Admin

Change Password