Kali Linux A to Z: Enable Routing

I am using a VM Workstation Player 17 for my kali, server 2003 etc. My nano ip_forward had 0 and when I changed to 1, I continue to get file is not writeable. I am using root. What could be preventing me from editing this ip_forward file please?

Can you share your terminal screenshot of what you did exactly and what the error is?