'4K titles'- meaning what exactly?? Please be more succinct in what content precisely looks good and what does not. Give specific examples if possible, and provide details on exactly which app/connected device/firmware you are using, and who your cable provider is too/connection speeds. (Via wifi or wired?)

I rarely find one setting that is adequate for *all* content. You would benefit from also posting your query in the dedicated AVS thread on that Sammy model. I own the 55" & 60" version of that 4K HDTV and so far, it's pretty decent overall. Some content is not perfect however. The gist of the settings can be obtained in the thread here:

http://www.avsforum.com/forum/166-lcd-flat-panel-displays/2387466-official-samsung-ks8000-ks8500-owners-thread.html

Here's the cache of info:
http://www.avsforum.com/forum/attachment.php?attachmentid=2261392&d=1501470490

Definitely peruse the FAQ before posting(!)