A client of mine had an issue with PayPal checkout option not working correctly. Site with eCmmerce 5.x-3.3, This was working correctly before. The issue was when a customer were sent to PayPal.com they were not presented with an option to pay via credit card. They are forced to login or create a PayPal account. My guess is that the field "PayPal processing URL:" needs to be changed. Which it turn out to be pointing to an incorrect URL.  The answer was to  go to https://www.paypal.com/xclick/