Paste the following in the active theme’s functions.php:

function paypal_checkout_icon() {
/* Replace the PayPal logo in WooCommerce Checkout */
return '[LINK TO IMAGE]'; // write your own image URL here

add_filter( 'woocommerce_paypal_icon', 'paypal_checkout_icon' );

Replace the link with the link to the logo/icon to be used.

Note #1: make sure to display the PayPal logo (see this post).

Note #2: if the size of the logo/icon cannot be changed, make sure to target only the credit cards icons in the CSS in other code edits (see post mentioned above).