In the newest version of Firefox the Proxy settings tab was hidden too deeply: into General -> Privacy and Security -> Scroll to the bottom -> Connection: Advanced settings -> Proxy settings. For many users switching between clear routing and some localhost socks proxy is a routine, and even usage of text search makes this operation annoying. Please make it accessible from the first layer of menu category, without falling deep into "Advanced settings". Or bring Connection settings into main menu.
Regards, true fan Gecko family!