Setting margins in page break preview

[Steve]

Old Excel easily allowed the dragging of the blue-line margin border just by
holding the mouse over the line, getting the double lines, and then dragging
the margin. In Excel 2007, I'm getting the blue line borders, but the mouse
on the line only produces a cross, and does not allow me to drag that line to
make a new margin.

How can I easily change the margins in page break preview.

Thanks,

Steve