WordPress eCommerce – Change Donation Label

I have just installed the latest version of the WP Ecommerce plugin and am interested in using the donation feature to allow customers to pay the amount of their choosing. I do not, however, work for a charity, so I need the label that says “Donation” to be changed to “Amount” or even removed completely.

I cannot seem to find the file where the label is set!

I have made the following change to /public_html/wp/wp-content/plugins/wp-e-commerce/wpsc-languages/EN_en.php:

changed this:
define(‘TXT_WPSC_DONATION’, ‘Donation’);
define(‘TXT_WPSC_DONATION_LC’, ‘donation’);

to this:
define(‘TXT_WPSC_DONATION’, ‘Amount’);
define(‘TXT_WPSC_DONATION_LC’, ‘amount’);

Yet when I pull up the product page, it still has the label as “Donation:”.

Any idea which file contains the text for this label? I’m looking for help specifically on the product listing page when “Purchase is a donation” is checked on the admin side.

many thanks!