The default AI integration doesn't seem to support this. The only thing I could find that does is called PageAssist, and it's a third-party extension. Is that what you're using?
So grab ollama and your prefered model, install openwebui.
Then open about:config
And set browser.ml.chat.provider to your local openwebui instance
Google suggests the you might also need to set browser.ml.chat.hideLocalhost to false. But i dont remember having to do that