Your Name at the top right > Account Settings > Change (next to password under "Accounts and Settings")
To change your password, log in to your account. Then click on your name at the top right of the screen, and click on "Account Settings". Under the "Accounts and Settings" section, click on "change" next to "Password". Submit your old password, then the new password twice. Click on the "Update Password" button.
*Note: You cannot change your VersatileKids password if your account is linked to your Facebook account.