The configuration is kept in the file /home/userxx/.vnc/xstartup I edited this file so that I can start the server with gnome. My file looks exactly like below.
#!/bin/sh
# Uncomment the following two lines for normal desktop:
unset SESSION_MANAGER
# exec /etc/X11/xinit/xinitrc
gnome-session &
[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &
# xterm -geometry 80×24+10+10 -ls -title “$VNCDESKTOP Desktop” &
twm &
