toxicTom: BIOS settings shouldn't mess with OS settings. And Win7 usually is pretty reliable with keeping settings. Some third-party tools might mess with them though - I don't know if you use stuff like that.
Nope, no "optimizers", if you mean anything like that. CCleaner, Mbam, JDownloader and such also don't mess with the settings. I have a "Taskbar Tweaker" (which would be closest to a third-party tool) but I've been using that for six years now as well and I don't think it ever gave me any trouble. And apart from that, it's just old games and 2-3 things I tried from Github regarding watching streams. I do definitely consider myself fit when it comes to PCs but I can't pin it down.