Aham that’s kind of limited for PayPal as of this moment.
For PayPal, you don’t need to do anything special, once they come back “from the same device” to the same funnel no matter what step, if they are still logged in to PayPal they’ll be using it to purchase, if not they’ll be using Credit Card as Clickfunnels does already.
But the limitation occurs when they come back to your funnel from a different device, at that point they’ll have to re-enter their Credit Card Information as they didn’t enter them at all previously.