Something happened to one of my menus

Hello:

One of my menus becamea a 1 column menu from having been a multicolumn one (can't remember if it was 3 or columns). However, it also goes all the way up to the top of the screen. I have tried to set Customize menu – Options – Maximunm sizes – Max menu height to various values, but to no avail.

How do I get a menu with all columns the same height and all columns fully populated, e.g.

xx
xx
xx
xx
xx
xx

or

xxx
xxx
xxx
xxx

or

xxxx
xxxx
xxxx


Regards,

Hans L