You can link either your Monese UK or EUR debit card or both. You have the option to do this when linking your PayPal account.
In order to link your card there must be at least £1/€1 balance on the cards otherwise it will not work. Once the cards have been linked, you can then choose your preferred way to pay online. Here you can choose either from your PayPal balance, or any of the Monese debit cards you added.
If you would like to unlink your Monese debit card, you will need to unlink your PayPal account in order to do this. Once the account is unlinked, you can then link your PayPal account again and choose a different Monese card to be linked.