The original hostname is associated with the backup set. Do your backups continue without any issues after the change? If so, is there any specific reason why you want to change the backup file name to reflect the new hostname?

I just ran one of my small daily backups, and yes, it seemed to have added the files to CBB_old_hostname. I guess that is what's important. one of my backups is to a removable hard drive which I put in a fire proof safe. Yes there is a label on the disk but I'd like the digital information to reflect which system it came from. I tried moving the existing destination backup files and running the backup plan, but it still used CBB_old_hostname.

It just seems wrong to continue using the old hostname, maybe that is my OCD coming through.

My OCD was too strong and I couldn't just let MSP360 continue to use the old hostname. I found the problem setting(s) in C:\Users\All Users\CloudBerryLab\CloudBerry Backup\enginesettings.list There is a tag <BackupPath> that contains the hostname (actually one for each plan). The GUI doesn't seem to expose this setting. In hindsight, I might have been able to create a new plan and it might have take the new hostname. Cloning the old plan didn't use the new hostname. But with the number and complexity of my plans, that would have been a lot of work.