Rename Your Computer
Your computer name is stored in two places in the /etc directory. To rename your computer you will need to edit both files. Open a terminal and:
gksudo gedit /etc/hostname
This file has a single entry, yourcomputersoldname change that to the new name you want then save the file.
Next, still in gedit, open /etc/hosts
It should look something like this:
127.0.0.1 localhost 127.0.1.1 yourcomputersoldname # The following lines are desirable for IPv6 capable hosts ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters ff02::3 ip6-allhosts
In the line beginning with 127.0.1.1 contains yourcomputersoldname change that to the same name you entered in /etc/hostname. Then save the file, exit gedit and close the terminal. I believe you need to restart at that point, though I’m not completely certain of that.