The homepage text is separate from the other pages on your website. It is located under the Widgets area of your website, which is typically located under the “Appearance” section in the left side of your administrator dashboard.
The specific widget position to modify does vary depending on which design you have:
Designs 1, 2, and 4: The summary text in the upper right corner is in the Header Right widget position. (The summary text shown under the photos elsewhere on the page is taken from pages each photo links to; modify those pages to modify the text that appears on the home page.)
Design 3: The homepage text under the slideshow is in the Slider widget position.
Design 5: The homepage text is in the Home Top widget position.
Design 6: The summary text is in the Search Bar widget position.
In all cases, the text widget is entitled “Visual Editor”.