For now there isn’t an option to control the widget’s headlines.
But you can change it by adding a function to the function.php file.
1. Make sure you are working with a child theme.
2. add this lines of code to function.php file (you can change it to <h3> if you want):
function pojo24475_setup_builder_widget_args( $args ) {
$args['before_title'] = '<h2 class="pb-widget-title"><span>';
$args['after_title'] = '</span></h2>';
return $args;
}
add_filter( 'pb_empty_widget_args', 'pojo24475_setup_builder_widget_args' );