No Extensions show in Customize Toolbar
All instructions for adding enabled extensions to the toolbar say to go to Customize Toolbar and find the extensions you want added there and drag them to the toolbar. However, when I go to Customize Toolbar, none of my enabled extensions show there at all, specifically those that are not on the toolbar. What am I doing wrong?
Alla svar (2)
Extensions are usually found at Menu -> Add-ons and Themes -> Extensions tab
Sometimes they end up in the Customize panel or in the toolbar Overflow Menu.
Others, like Dragon NaturallySpeaking, are actually installed as a Plugin Menu -> Add-ons and Themes -> Plugins tab
I notice, in your screenshot, a "dead" space on your toolbar which may be the extension that you're looking for but is "blacked out" by your Theme.
As a last resort, you can go to Customize Toolbars... and click on the Restore Defaults button.
Customize Firefox controls, buttons and toolbars
https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars
In case you use Private Browsing mode, see: