Updating JetBackups to an EDGE version is done through the command line as the root user.
If you are on the latest STABLE JetBackups version as of June 1, 2021, then you are running version 5.1.10. You will need to run this command to update to the EDGE tier:
jetapps -t jetbackup-cpanel edge
Once you've updated to the EDGE tier, you'll be on version 5.1.12, which means that going forward, you'll be using the following command to change the tier:
jetapps -t jetbackup5-cpanel edge