Can't find the php to alter checkout text

[bhensarl]

I'm attempting to edit the text on my checkout success page because I can't find the php file that is populating the text. Here's the code for the checkout success page itself:

<?php if (DEFINE_CHECKOUT_SUCCESS_STATUS >= 1 and DEFINE_CHECKOUT_SUCCESS_STATUS <= 2) { ?>

<div id="checkoutSuccessMainContent" class="content">

<?php

/**

 * require the html_defined text for checkout success

 */

  require($define_page);

?>

</div>

Can someone please point me in the right direction? I know I altered this file initially, but now I can't find it again. Thanks.
Brian

[nigelt74]

includes/languages/english/checkout_success.php

or it should be

includes/languages/english/YOUR_TEMPLATE/checkout_success.php