Login to the client portal at https://www.astutium.com/clientarea.php
Select "My Services , List"
Click the "View / Edit / Manage" button
You can access / update your password for your service on the Password tab.
*Please* only use a unique password, containing at least 8 characters including numbers, letters and punctuation so it's not "guessable" if you change it. A good way to select new passwords is to take a phrase you'll remember and take the first and last letters of each word, including any punctuation where necessary and replace the letters that look like numbers (l33t speak, for example - e becomes 3, 1 can be an i or an l, etc.).