Despite recently starting to allow users to opt for HTTPS on all sessions, Facebook clears the setting with no warning when people try to access most apps. The social networking site prevents this from happening automatically via a dialog that reads “Sorry! We can’t display this content while you’re viewing Facebook over a secure connection (https) To use this app, you’ll need to switch to a regular connection (http),” Facebook users can’t use HTTPS for all future visits. The site recently announced a new “secure browsing” option located under the Account Security menu.”]
Source: https://news.softpedia.com/news/Facebook-Clears-Permanent-HTTPS-Setting-Without-Warning-182996.shtml