A: The suggested titles are the ones that you have added to other contacts before. If you have fetched a contact from the database with a title, this one will appear as a suggestion as well.
Suggestions appear once you start typing in the Title field. They show up to 10 existing titles that start with what you have typed.
If you want your team to pick from a fixed list of titles instead, use the Title category field. See How to use title category with contacts.