Thank you for your post.
Most likely, the person is doing a three-finger upwards swipe to hide the Menubar, and a three-finger downwards swipe to show the Menubar.
To prevent the Menubar from disappearing, create a script that shows and locks the Menubar. You can put this into an OnLayoutEnter script trigger that includes the script step:
Show/Hide Menubar [ Lock ; Show ]
Users will then be unable to hide the Menubar unless there is another script that hides the Menubar.
Let me know if you need additional clarification.