Hello,
However, These steps tells how to change a MySupport password after logging in and how to reset a password if the password is forgotten.
1. How to change a MySupport password.
1-2. From the Main page, click "Click here to manage your account information".
1-3. Click "Change Password" under Account Actions.
1-4. Enter a new password and click "Change Password".
NOTE: Please follow the password rules: maximum of 12 characters with no spaces.
1-5. Click "Change Password" and the new password is saved. Please use the new password the next time you log into MySupport.
2. What if the password is forgotten.
2-2. Enter your email address and click "Reset Password".
2-3. The screenshot below shows the confirmation for "Reset Password Success". The new password will be emailed shortly. After you receive the new password, follow the steps above "How to change a MySupport password" to change the new password to your preference.
Also, check the Following Symantec Knowledgebase Article:
How to register and validate your account for Symantec's MySupport
http://www.symantec.com/business/support/index?page=content&id=TECH52352