You'll need to choose interests until the progress bar at the top of the screen is filled. Some topics will fill up the bar more than others because some topics have more characters or names associated with them.
If you're having trouble filling the bar, try selecting things like TV shows or movies since those interests include many characters, whereas selecting individual people only counts each selection as a single person.
Progress bar at the top of the screen
Not sure what interests are? Click here!
Want to suggest new interests? Click here!