By default WooCommerce reports consider "on hold", "processing", and "completed" statuses as successful sales in the reports. I personally think only the "completed" status should be considered as a successful sale. To change WooCommerce reports to be inline with this:

Open functions.php in your child theme and add the following:

add_filter( 'woocommerce_reports_order_statuses', 'my_custom_order_status_for_reports', 10, 1 );

function my_custom_order_status_for_reports($order_statuses){
    $order_statuses = array('completed'); // your order statuses for reports

    return $order_statuses;
}

Save the file and view a report. You'll notice only orders with the completed status are shown as successful sales.