changing $DISPLAY to :0

I have an application which requires $DISPLAY to be :0

if I install rhel 8.5 fresh, then DISPLAY is :0
But when I install the proprietary NVIDIA drivers needed for my application, the next time I log in (X11 desktop now) DISPLAY has switched to :1 anbd my application wont launch

my limited thought process is something to do with wayland being the default on install, and then nvidia drivers default to X11 ?

I have tried to enable nvidia for wayland and booted into both wayland and x11 classic desktops - but each report display to be :1

How can I get my desktop back into :0 for X11 ?

any help would be appreciated

Thanks