Sorry, seems I wasn't notified of this review. The settings are linked to your browser. It prefers synced storage (tied to your Firefox account), but also uses local settings. If it forgets settings, that's likely a configuration issue on your end, and should also happen for other addons. If it's only Enhancer for Nebula, please open a new issue at https://github.com/cpiber/NebulaEnhance/issues/new with additional information

Please open a new issue with this suggestion on https://github.com/cpiber/NebulaEnhance/issues/new as I'm not sure what you mean. The extension performs a Nebula Search for the YouTube video if it cannot find it on the channel (Note: The channel must be registered on https://standard.tv/creators/ for that, please mention the channel if you think it should be but isn't)