I'm trying to create an exception file to disable my ethernet as I think it's responsible for my 350s+ boot times, please see section of dmasg below :-

[ 3.750961] sd 6:0:0:0: [sdb] Attached SCSI removable disk
[ 364.079424] ADDRCONF(NETDEV_UP): eth0: link is not ready

I'm following this answer Disable Ethernet permanently to speed up boot time and I've created the file but I can't save the edited version, the permissions tab tells me it's owned by root.

Any help is most appreciated. I'm a proper linux newbie, trying to get it to work on this laptop is my first foray into Ubuntu. I read messing with the root 'account' is not something for people who don't know what they're doing (i.e. me!). Please be gentle :-)