Using the current nvidia drivers needs a system (2)reboot to work. so it works only on a (2)hdd install.
Guess it works on the next test iso when also the (1)nouveau driver is on the livecd.
I was able to pick nouveau
from the X-section in that PCC choices.
Yes I know that should work by reboot but my goal was to cnange the resolution only
and I have a partial success which must include changing of video-card and after that
monitor/resolution. Logout/login and the LiveCD resolution is altered.