Cookie Override af Rafal Bielski

The extension allows to add rules overriding specific cookie values whenever a website producing the cookie is visited. This allows, for example, to persist and force website preferences like language and location despite removing cookies on browser exit. The preferences can be stored as rules in the extension settings and applied automatically when a page is visited, while keeping the page unaware of the user's previous visits.

More information
https://github.com/rafbiels/cookie-override

Known limitations
The override cannot work on any website which uses scripts to auto-configure the cookies on every visit even if the cookie is already present. Such scripts keep overriding the Cookie Override changes.