Lxde login panel resolution

Hi
Env Debian 9.12 using LXDE
i set lxde video resolution to 1024x768 and it works fine
but when lightdm is started it show me the login panel in very high resolution ..with small fonts and small input fields
according to some hints i create a script lightdmxrandr.sh
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#/bin/sh
xrandr --output VGA-0 --primary --mode 1024x768
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(i tested the script and it works)
then in lightdm.conf at bottom i insert a line with
display-setup-script=/home/bong/Documents/lightdmxrandr.sh
but nothing changes ..still login shows in high resolution ...
Looking at the small icon i see F1 to set big fonts and this helps a little,but at every boot this setting is resetted to small fonts ...
in the past i used xorg.conf to set parameters...but debian 9 does not use it anymore,it sense the hardware and starts display manager with the higher resolution available ...
how to set the login panel at 1024x768 ? or big fonts at login permanently ?
thanks in advance
Maurizio