Device remembers old IP in port forwarding only

My NAS needed to get a local IP change. While the device details reflects as such, whenever I try to set a port forward to it, it recalls the old IP (once the port forward is set, it says "no device assigned" and the IP is the old one). I'm not sure how to refresh the list, and due to the xfinity software only allowing me to select by device name and not IP, I'm unable to manually set the IP.

How do I refresh the port forwarding device list so the new IP is what's used? Alternatively, how can I access a more advanced display so I can manually set the IP?