What should I change to fit my screen size (1920x1080) ?
That looks like the untouched version, because "videoscreen.whitelist" is empty. If it's not stored in the ".kodi" folder, than it's just the template, not the version that LE actually uses. That's why I think changing the file doesn't makes sense. Where does it come from, what's the path in LE? If you don't have the ".kodi" folder, updating "guisettings.xml" can't work.