Welcome to the official community for LibreWolf.
LibreWolf is designed to increase protection against tracking and fingerprinting techniques, while also including a few security improvements. LibreWolf also aims to remove all the telemetry, data collection and annoyances, as well as disabling anti-freedom features like DRM. If you have any question please visit our FAQ first: https://librewolf.net/docs/faq/
To learn more or to download the browser visit the website: https://librewolf.net/
If you want to contribute head over to our Codeberg: https://codeberg.org/librewolf
I suspect that you'll find answers here:
https://old.reddit.com/r/firefox/comments/7dvtw0/guide_how_to_edit_your_context_menu/
That link came from more documentation here:
https://www.howtogeek.com/334716/how-to-customize-firefoxs-user-interface-with-userchrome.css/