Volumes may be moved from one VM to another. In Horizon the volume must be detached from one and attached to another. Detaching is not possible, however, from a running machine, which must be stopped first. Appropriate system reconfiguration should also take place: on the old machine the entry in /etc/fstab must be removed or commented out by editing file using a command (be extremely careful while applying changes!):
sudo -e /etc/fstab
and new machine must be configured as in How to attach a volume to VM?