This guide will teach you how to make Firefox display the full URL of web pages in the address bar (restore the missing http://). This procedure requires that you edit the browser.urlbar.trimURLs browser property.
Display the Full Website URL in the Address Bar
Open Firefox and type about:config in the address bar and press Enter. A warning message will be displayed, click on I'll be careful, I promise! to proceed to the about:config page. Search for the browser.urlbar.trimURLs property and set its value to False:
Once done, close the about:config page and resume your browsing session.