There is no profile icon on her app, @Anonymous? Or there is, but the next screen does not include the option to switch? Either way, that is strange. It should work on her phone exactly the way it does on yours. There are no separate hosting and travelling apps. Without being able to see what you see, I would say to try deleting it and then reinstalling.
And sorry about not being clear with the tagging (@) advice. You need to type @, but then click on the person you want from the dropdown that instantly shows up. I told you to type @ before the name, when I should have said type @ and then choose the name.
Will you let us know what happens when/if you reinstall the app?