Hello There,
I have logged in and checked your custom headers. It seems that all the custom headers were unassigned yet.
Please assign the header to a page or globally before it will take effect in your site. Currently, the header is displaying the default one because no custom header were assigned.
I also checked your custom header and it seems that both the buttons were hidden in smaller screens. Please click the buttons, find the “Customize” tab and make sure that the “Hide During Breakpoints” is disabled. When enabled, of course the element is hidden in the screen size which you have selected.
To know more how the “Hide During Breakpoints” works, please check this out: https://theme.co/apex/forum/t/hide-during-breakpoint-explained/17378