Mike,
If by expand, you mean have the row height automatically increase, use
Format - Rows - Autofit. If you manually adjust the row height, it turns
off Autofit. With Autofit on, changing the size (font) will cause the row
height to adjust automatically to accomodate. If you have Wrap Text turned
on (for a multiline cell within the cell's width) (Format - Cells -
Alignment) the row height will adjust as you add/remove text from the cell.