How do I replace domain.com/wordpress with domain.com on Amazon AWS?

I just installed a Bitnami WordPress AMI instance on EC2 and pointed my custom domain to the public domain for this instance. However, the URL changes from domain.com to domain.com/wordpress. I assume this means that the default AMI puts WordPress in a separate directory. When I go into Dashboard/Settings/General, both the WordPress Address (URL) and Site Address (URL) are not editable. Why, and how do I change this to just domain.com? This newbie would greatly appreciate any assistance that you might be able to provide. Thanks!