The Stripe account that you have connected to this website must have pay outs set to manual. I will show below in a video how to do this.
If your pay outs are set to automatic – Money will be in transit to your bank and unavailable when you try to process a refund to customers. If the pay-out is manual, you can choose when and how much to withdraw to your bank account and can manage your funds so that they are available if a refund is required
Please always email the website Support team for help if you are unsure.