Hi @bill, welcome to the forum!
You can find more information on this in the documentation:
disclaimer Upon re-reading the documentation, it seems that is not the way to do it correctly (as we shouldn’t run software on dispVMs)
Explanation hidden (read above warning)
But in summary you run in dom0:
# open a terminal from fedora-32-dvm (or your desired Disposable Qube)
qvm-run fedora-32-dvm gnome-terminal
And then on the newly opened terminal you type:
firefox
then firefox will open and you customize it however you want (but don’t use for anything else there – like browsing the web)
Then close firefox and shut down the DispVM Template with sudo poweroff
Finally when you open your DispVM those changes should be applied
This begs raises the question, then: what is the recommended way of customizing software in dispVMs? If we are not supposed to run software in its DispVM Template? Are we supposed to tell people to edit configs on text files by hand? Or is there a more usable way?