Usually the return window is just a few days. This sounds defective on arrival so make the calls to seller and Samsung to see if they can correct this either by repair, settings or exchange.
So bought this year, and its connected to Comcast for cable....and it skips Picture goes dark for 1-2-3 seconds then re-appears). I have Samsungs in other parts of the house also on Comcast with no problem. I also have no problem on the 78 watching Netflix or any other app. Only when Comcast is on is this a problem and only on the 78. Any thoughts on the problem?