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If you're referring to the payer's info, then this is not editable, your submitter will need to purchase the product or submit the form again if some info needs to be updated.
If you're referring to your info in the payment integration, then this should be possible to do by clicking on the payment field and then click on the wizard icon, I see that one of my colleagues replied to you with more information about this on the thread on this link: https://www.jotform.com/answers/828811-how-can-i-edit-paypal.
If you have more questions feel free to let us know, we will be glad to help you.