These instructions explain how to clear Firefox 29's cache. This is sometimes necessary if sites have made changes and you are not able to see the changes. All browsers store temporary copies of web page elements such as images, and the text to allow you to return to the page without having to wait for the files to transfer again. Normally this works well, however, sometimes the browser does not detect that the files on the site have changed so it continues to use the temporary copy instead of the new file from the server. By clearing the cache you force the browser to retrieve the site from the server which will give you the new version.
Go to the bars in the top right corner, and down to Options
Click the Privacy tab, make sure Remember history is selcted for "Firefox
will", then click "clear your recent history".
Select Everything at the top, check Cache (and anything else you want to
remove, and and click Clear Now.
Click on OK to close the Options window.