Go to 'Orders > 'Show refund alerts' button. If there are refund requests waiting to be approved/revoked, a red dot will appear in the button. in order to see those requests, click on the button. The requests are printed in bold text and are marked with a blue asterisk (*) in the order overview (only if you're administrator or authorised user).
You can find a list with processed refunds via Orders > Advanced search > Fill in the dates > Select State 'Refunded' > Search.
In the back office you'll find an overview of all refunds in a certain period (including the status) via Reports > Refund Requests Overview. Adjust the dates (if necessary) and click on Show refund requests.