Hi Peter

By default, this option is not available with this template however you could try adding the following to the Custom CSS field of your template style settings...

#hornav .columns-2 + ul {

  -moz-column-count: 2;

  -moz-column-gap: 0;

  -webkit-column-count: 2;

  -webkit-column-gap: 0;

  column-count: 2;

  column-gap: 0;

  width: 420px;

}

#hornav .columns-3 + ul {

  -moz-column-count: 3;

  -moz-column-gap: 0;

  -webkit-column-count: 3;

  -webkit-column-gap: 0;

  column-count: 3;

  column-gap: 0;

  width: 630px;

}

#hornav .columns-4 + ul {

  -moz-column-count: 4;

  -moz-column-gap: 0;

  -webkit-column-count: 4;

  -webkit-column-gap: 0;

  column-count: 4;

  column-gap: 0;

  width: 840px;

}

Then try enabling as detailed here.. https://joomla51.com/tutorials/template-extras/creating-multi-column-dropdown-menus

Ciaran