You need to install the File Manager plugin (read here) and that will give you access to the file system. With that you can edit the settings.js on the iHost.
And check this article on how to configure access to the Node-Red editor. That should fix your problem.
As the guide suggestes you can run node-red admin hash-pw to generate the hash for the password, but I have no idea how you can run that on the iHost.
Also keep in mind that after all these changes the editor is still accessed via unsecure http communication. Therefore I would not open up the port and make it accessible via the internet.