Xpertiz - Header and Footer
The Headers and Footers on the Xpertiz theme are controlled through ElementsKit, not through the theme settings in the Customizer.
You can usually find the ElementsKit menu at the top left of the WordPress dashboard.
Go to the Modules section, you will find a list of various modules. Make sure the Header Footer module is activated.
and you can start editing the Header or Footer section by clicking the " Edit with Elementor" link
you can also click directly from the link available in the Admin bar
You can even make your own Header or Footer section. Click the My Templates link under the ElementsKit menu, then click the Add New button
Type the Title, then select Header, Footer or Section type from the dropdown, then you can select the condition needed i.e. Entire Site, Singular, or Archive. Set the Activation to "On". Then click the "Edit content" button to build your own content. You can add any widgets and build the Header, Footer or Section you need.
If the content has been built, then click the Save changes button.
You can find the documentation link from the ElementsKit Dashboard if you need more information regarding other available features.