Open your browser and head to the login page https://tass.riverside.qld.edu.au/ParentLounge

Use your Parent code (also called Account number) as your username. Click/tap on Forgot Password
 

Enter your parent code as the username, your email address used for receiving Riverside emails and the Security Code shown (changes every time) and click/tap Save

Check your email, including SPAM folders, for an email  from college@riverside.qld.edu.au similar to this and click/tap on the link included in the email.

Choose a new password and enter it in both boxes then click/tap Save.

You should get a confirmation pop up.
 

You can now return to the login page and log in using your new password.