h3disp dynamic framebuffer size

before I used the -f option with h3disp, the framebuffer would always take the same size as the display resolution I'm setting. However, since I used the -f option once, if I now use h3disp without the -f option, the framebuffer size remains locked to what I had set before, even if the display resolution changes as requested. How can I set it back so that the framebuffer always takes the proper size when I use h3disp even without the -f option?