In the real world the writer writes the logline. It is used to interest a
producer who then reads the script. The producer will then use the
logline to interest a director in the project. The producer (or an assistant)
may rewrite the logline. Once a director is involved there is rarely a
need to change the logline. But yes, the director can change it. After
the movie is finished a logline is used for marketing and could be changed
my the advertising agency.