The random quote is actually a HTML Rotator that can be setup to rotate HTML, Images, text, etc..  To edit the HTML Rotator, please do the following:

1. Log into your e-Store Control Panel
2. Click on the Content tab
3. Select Home Page from the category bar to the left
4. To edit the quote, press the Edit button next to the quote, as shown below, otherwise, press the Delete button

5. Make any changes you need, then press the Save Changes button