A factory reset will reset the settings back to factory settings losing any custom settings, hence the name "factory settings" You have option to reset the GEO, the settings or all. Reset all will delete all custom settings and programs, reset settings will reset just the settings but will not depete any of the custom programs you made or uploaded. If your going to change coils you should turn the detector off to do so, when you turn it back on it is set to go...