Activated the Pay by Card via PayPal option. Works great if creating new invoice. But existing recurring invoices are sent without this option being activated.
The option to Pay by Card hasn't automatically been applied to all my recurring invoices. Firstly, I don't see how to do this as editing the recurring template only allows you to select "allow customer to make payment", which doesn't by default select PayPal as well, but also I have 1000's of recurring invoices so don't want to have to change each one manually.