Yours is a theme that is designed to display automatic excerpts.
It is also a retired theme that does no support all WordPress features.
1. Choose a theme designed to display full posts. Themes that automatically provide excerpts on the front page are listed here http://en.forums.wordpress.com/topic/theme-with-automatic-excerpts?replies=13#post-1396410
2. Create an excerpt on the theme you currently use by using a workaround to display full post.
Fresh and Clean is a theme that provides automatic excerpts on the front page. As it does have an active excerpt box below the post editor, you can control the length of the excerpt displayed and the exact excerpt that is displayed . This is the workaround you can use to override excerpt display on the front page.
You compose your whole post first and before you publish it you switch to the HTML (Text) editor, copy the code for what you wish to appear, paste it into the Excerpt box below the editor, and publish the post. http://en.support.wordpress.com/splitting-content/excerpts/#creating-excerpts
If you want to create your own excerpt for each post then that will have to be done on every post.