Accompanying that is a request for your username or email address and password.
Interests are displayed front and center.
Thankfully, that process is similar enough between devices that we can walk you through a solution to this problem fairly succinctly.
To the right of your search bar, near the link that will lead to your personal profile, is a drop-down options menu.
Mobile Conveniently, the process described above for logging out of the desktop Facebook application works just as well on mobile, and quite nearly the same way.