You would need to modify the file yourself in order for this to happen:
Hopefully this will be added very soon.
File: template.php
Line 1217: Modify like this
<!– <legend> //–><?php //_e( ‘Billing Details’, ‘give’ ); ?><!–</legend> //–>
<legend><?php echo apply_filters( ‘give_checkout_billing_details_text’, __( ‘Billing Details’, ‘give’ ) ); ?></legend>
And then you can use the new filter in your functions.php file: give_checkout_billing_details_text
Hi there,
A couple things:
1) Please don’t change the core files of the plugin. We cannot provide any support in such cases
2) Billing Details are for credit card confirmation and are therefore very different from Shipping details. Just keep that in mind in case donors Credit Cards start getting declined.
3) We don’t have plans to add a filter for that specifically because of #2 above, but if you need to change it, it’s better to make your own localized .po file and update it that way. That way you get the desired result without changing core files. We cannot provide support on creating your own .po file but we do have this article that can serve as a guide: https://givewp.com/documentation/resources/translating-give/
Thanks!