Within the software there are two areas to change the terms and conditions the software comes installed with. The first one is the terms and conditions page linked to from the footer of the default design. That page is an extra page in the system and uses an extra page body template to contain the content for that page. You can edit this template using the following admin tool:

DESIGN > MANAGER

and you'll find that template within your custom template set here:

/main_pages/extra_pages/terms_and_conditions.tpl

The second terms and conditions the software uses is the one displayed within the registration form for the software y default. Look to make changes to that "text" attached to the registration form here within the admin tool:

PAGES MANAGEMENT > REGISTRATION > Registration Information Collection/Cancellation Page > [EDIT TEXT]

You'll see "Registration Agreement" just a couple down.