How to transition from the Paypal or Stripe module to PrestaShop Checkout?
Updated
Once Checkout is installed, log in to your PrestaShop Account.
Locate the Checkout module in the module manager and click on "Configure".
Follow the setup steps for the module and your PayPal account.
When the Checkout payment methods are activated (LIVE on the interface), and you find them in the purchasing process of your store, go to "Payment Methods" in your back office and deactivate the other payment modules.