nixCraft published a quick tutorial about changing the Hostname in Ubuntu 20.04.
How to Change Hostname on Ubuntu 20.04
How do I change the hostname on Ubuntu 20.04 LTS Linux system permanently? This step-by-step page shows commands for changing the hostname on an Ubuntu 20.04 LTS system. Please note that the hostname set at the time of installation either by sysadmin or cloud service provider such as Linode, AWS, and others. To change the Ubuntu computer name, you must log in as the root user. The best way to do this is to use the sudo command.
How to Change Hostname on Ubuntu 20.04
