This may be because you have not published your store pages.

Sign in to your Store Editor and look at the Editing Toolbar on your front page. If the [Publish] button is yellow , you need to click it to make your changes live. The button will be grey and read "Published" if the store is already published.

Once the [Publish] button is grey, you can view the changes live by refreshing your browser at this URL:

http://store.yahoo.com/accountname

If you are still not seeing your changes, then you may need to publish again. Edit your store, go to the Variables page and click [Update]. Then publish your store again.