resizing the Preview window

Searched everywhere online, no answers. Does anyone know why Preview windows only resize to approx 5" Width, even though Height is much smaller? This drives me crazy when working with multiple images of my art, and there is that extra 3" on each side. Even when removing everything possible from toolbar, doesn't change anything. It is NOT in settings for Preview. There is no way to add a comment on apples app page, they do not include Preview!! This is a serious hitch in my giddy-up.