You need to change the IP number in httpd.conf and also in any IP-based virtual hosts either in httpd.conf or files that are included by httpd.conf.
It seems that you tried to do that, but failed to over-write/save the file and the changes.
If root is not able to modify a file, then the filesystem might be mounted as read-only.
I don't see why you ant to change file permissions on a file to 777 when accessing that file as root anyway.
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