If you are in your MyUnyte account and know your password, you can change it by clicking on your name in the upper right-hand corner. Click on 'Change Password.' You will need to enter your old password in this case.
If you don't know your password, be sure you are logged out of your MyUnyte account. The log out button is accessed by clicking on your name in the upper right-hand corner of the dashboard.
Then go to my.unyte.com and you will see the login screen. At that screen, use the 'Forgot my Password' link. You will receive an email to reset your password that doesn't require your old password.