Hello Hrussell, please follow the next steps to download and install firefox: 1. Download a copy of the latest firefox from http://www.mozilla.org/en-US/firefox/all.html (full dmg package) 2. '''Trash''' the current Firefox application to do a clean install. 3. Install the version that you have downloaded. Do not select to remove your personal data, your profile data is stored elsewhere in the [http://kb.mozillazine.org/Profile_folder_-_Firefox#Mac Firefox Profile Folder], so you won't lose your bookmarks or other personal data. see also: [https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac How to download and install Firefox on Mac] thank you