Can edit, but can't write to config.inc.php even with sudo command (permission denied)?

I'm trying to set up a XAMPP server to host Wordpress locally while I develop the theme for it. I followed the directions and had trouble connecting to my localhost. I tried changing the port to 85 and that just broke everything. With the default port 80 I was able to view the XAMPP home page (by clicking on "go to application" in the software or typing in my IP). However, I could not get Wordpress to install since the site itself goes blank and wouldn't display.

So I've now landed on changing anything that says "localhost" to my IP and an error message actually appeared saying that it had an error with establishing connection with the database. So I'm assuming it's because I had to change the host address in the config.inc.php file from localhost to my IP.

The annoying thing is that while I've researched and found a way to edit the file in the terminal. It still won't let me proceed with saving my edits. Anyone know how I can solve this problem?

Thanks!