You could create a many to many relationship between 2 tables in a database. The two tables would supposedly be a users table and a table with all the titles. That would be one way.
You could also store a serialised array in the users table of all the titles in their list.
It would be easy to update the list and display it as you needed using those methods.
There are other ways but those two are probably the best options from the ones in my head. :-)
“The best thing about a boolean is even if you are wrong, you are only off by a bit.”