Mobile Menu Has Different Pages/Page Names, Different Order than Desktop

I’m helping my brother build a website for his small business. We’re almost done, and when we went to test it today, we found the menu on mobile shows pages with wrong names, pages that shouldn’t be visible/don’t exist, and displays them in the wrong order. I came across this forum post that describes my issue closely, but the solution doesn’t fit my problem. https://wordpress.org/support/topic/mobile-menu-210/#post-14772224

Imgur Link: https://imgur.com/a/qQnsXLs

The page I need help with: [log in to see the link]