Set Print area on large sheet

[Marshall]

I have a simple sheet with 1887 lines and I can't seem to
be able to drag the Print Area outline (in Page Break
Preview mode) on the bottom of the form. It allows me to
move the Vertical line, but not the Horizontal line. If I
add text to a cell outside the print area, the Print area
is automatically expanded to fit around that new text, but
if I wish to expand it further, or shrink it, I cannot
drag the horizontal blue line at all. What is wrong?

Thanks,
Marshall