Either every time the browser restarts, or when the addon updates, the settings are reset. Automatically filling login information is extremely annoying for developers and QAs, we have multiple and need to choose, and if we try to choose while Auto-fill is on, it will keep overwriting what you chose, making it unusable until you change the setting. And perpetually change the setting. It's a horrible user experience. Persist settings changes because that's the point of having settings.