[Theme Horse Support Team]

Hi Jeremy,

Login to you WP dashboard and go to the Appearance > Customize > Ambition Theme Option > Custom CSS then paste the following CSS code and Click on Save & Publish button.

#colophon .widget_nav_menu {
    text-align: center;
}
#colophon .widget_nav_menu li {
    display: inline;
    float: none;
}

Also please edit or customize the CSS code via Custom CSS option as above OR do create child theme to customize the main CSS code.
If you edit the main CSS code directly in style.css file then you will lost your edited code after you update the theme and you will have to edit it again and again each and every time you update the theme.

Thank you!