@User: Probably this means that you created the label without a rendered font, so it's stuck with a fixed-pixel-size X11 font. Since the arguments of the "label" command are complicated, it's easier to use the Edit->Text... menu button to get a pop-up window from which you can select text font, size, rotation, offset, etc. You can change from the default X11 font to a rendered font using this pop-up window.