Most likely, you're talking about TruMotion (on LG), MotionFlow (on Sony), or similar technologies from other brands - it's frame interpolation that adds smoothness to motion. But honestly, there aren't that many "hidden" settings in modern TVs; usually the useful options are right there in the regular menu. The most useful one for picture quality is the picture mode. Try switching from "Dynamic" or "Bright" to "Cinema" or "Standard" - those usually have aggressive filters turned off, and the picture looks more natural.
If you want to dig into the details, go into the advanced settings (often called "Additional" or "Expert") - you'll find controls for sharpness, contrast, and color temperature. I noticed on my TV, for example, that some kind of "dynamic contrast" is enabled by default, which makes the picture look unnatural. I turned it off and it got way better. It also helps to turn off filters like TruMotion if you're not watching sports or action movies - for films and series they often have the opposite effect.
The exact path to the settings depends on the manufacturer, but it's usually: menu → picture → mode → select, or additional options. If you want to read up on your specific TV, check the manual on the manufacturer's website - it's explained in more detail there. And honestly, a year without optimizing isn't a tragedy; you just know now that it's easy to improve.