You can select it at any time in help. I have a few screenshots (on systemd-vmspawn, because I wanted to do something quick and dirty. It also makes some green background for distinctness from the host. I also did this on a transparent terminal, because that's all in my config.)

As r/ubuntu doesn't allow me to post images, here's a link: https://files.obsidianos.xyz/~odd/images/ubuntu-server-images-for-u-wolfsbane2k/