I have EOS running on my laptop perfectly with Gnome, and thought I would try KDE in a Boxes VM.
I have the latest copy of ISO version of EOS. I create new a new virtual machine in Boxes complete the install and get to Liveuser install. I then complete the full install with KDE desktop. The installation shows done, and I then try to restart EOS and I go right back to Liveuser mode. What am I doing wrong? Why won’t EOS install like other distros in Boxes?
I think you would need to go to the VM:s properties. If I remeber correctly you could choose what device it can boot from or you could open some config file from there and change the boot order to the virtual disk.
Sorry for not being more precise. It was quite some time ago I used gnome-boxes.
EDIT:
Right click on the VM and choose Properties: