Hi Makemeri,

From template Options you can:

1. Change height of header where the menu is
2. Change color, font size and font-family used in menu
3. Change width and align of submenu

Whole rest you have to make using custom CSS. Some tips you can find here: https://www.joomshaper.com/documentation/helix-framework/helixultimate/faq-how-to-do

I would like all menu items to fit on one line on the menu bar.

Iam using the Indigo template