Support Forum

This button is using standard GP styles, so the Customizer should definitely work: https://www.screencast.com/t/eXEpSgTwlE6J

You can adjust the text like this:

add_filter( 'wpsp_ajax_load_more', function() {
    return 'Load more';
} );

add_filter( 'wpsp_ajax_loading', function() {
    return 'Loading';
} );