Below the Editor window, there is the “Excerpt” field. This will allow you to control what will be shown on the recent story list or the story archives. Important to note is that if you leave the Excerpt field empty it will automatically grab 100 characters and kill any formatting, so that will not look very appealing.
Another indicator of a lacking excerpt is due to how TFT is setup, it will actually show 2 “read more” links, which is technically a bug.
Good practice involves either simply copypasting 1 or 2 paragraphs into the Excerpt field, or writing a synopsis of your story.