This WooCommerce code snippet enables you to change de paypal icon-image on checkout page

oaf_change_paypal_icon_image.php

<?php
/**
 * This WooCommerce code snippet enables you to change de paypal icon-image on checkout page.
 *
 * Author: Oscar Abad Folgueira
 * Author URI: http://www.oscarabadfolgueira.com
 *
 * You can copy this snippet and paste in your functions.php or you can build your own plugin
 *
 * Change the image for other you want.
 */

// This funcition returns the url of the new paypal image
function oaf_change_paypal_icon_image() {
     
     return "http://www.oscarabadfolgueira.com/wp-content/uploads/2016/03/icono-paypal-tarjetas.png";
}

add_filter( 'woocommerce_paypal_icon', 'oaf_change_paypal_icon_image' );