On your GCash app, go to Menu > My Account > Paypal

If you have successfully linked your Paypal before, the email field is pre-filled with the Paypal email that is currently linked. To change this, tap the email field and input a new Paypal email.

To confirm that you’re changing the linked Paypal account, the app will prompt a message, “Oops! This GCash wallet is already linked to {currently linked email}. Authorizing a new Paypal account will unlink the existing one. Do you want to proceed with linking a different Paypal account?” Tap YES to confirm.