Modify the system name and version number displayed in "lsb_release -a" and "Settings-About-Operating System Name"
Open the terminal:
1. Modify the lsb-release file: sudo gedit /etc/lsb-release
2. Modify the os-release file: sudo gedit /etc/os-release.
Change the number indicating the version into the desired version number. The number is sufficient, as is the system name. You can change it as you wish.