Hi there,
Thanks for writing in.
You may have multiple menus like having a menu per each device, example, inline-menu for the desktop which you should hide from mobile and tablet devices. And you can hide them by inspecting the elements then go to visibility options from customize section.
The same goes for mobile menu(like collapse menu), you can hide it from desktop.
I checked your site and you have the correct setup, but I recommend using the collapse (navigation collapse) menu for mobile instead of a dropdown (navigation dropdown) menu.
Though, I’m still unsure what you’re really trying to achieve, would you mind providing a video recording of the said issue? You said it’s when editing in cornerstone so I may need your login credentials as well, please provide it in a secure note.
Thanks!