Problems with TV as Monitor

Hi everyone. I hope I can get some actual answers here and this forum isn't run by the same customer service in India.

I just spent 2 hours on chat with tech support (INDIA) trying to describe and solve my problem with my laptop. They don't understand or have the technical ability to do this job if your problem doesn't fit into their scripts. And it's not a hard problem to understand. My new Inspiron 3558 is plugged into my Sanyo LCD TV at home. I use this as my sole monitor when home. I had a Inspiron 1574 hooked up to this tv for 7 years with zero problems. 2 days later I plug this new system in, and the computer keeps trying to change the resolution on me all by it's self. The chat with Dell in INDIA took the tv model number and tried to tell me that it doesn't support the resolution I'm trying to use. WRONG! It states right in the tv manual it supports every single resolution my computer can. I'm just looking for a way to stop my computer from trying change the resolution! Instead I got maybe it's my HDMI cable, your tv doesn't work right. I was going to buy the extended warranty but if i ever have a problem this is kind of help I can llok forward too for a price?

So while getting on here they messaged me again saying that it is my TV. Well here is what they just said "The Resolution of the TV is 1920 x 1080 for Full HD whereas the laptop supports 1366 x 768 HD resolution. Connecting the laptop to the TV the resolution would remain 1366 X 768 hence it’s a compatibility issue. Do let us know if you need further assistance."

Now I have an older Dell laptop and my wifes Toshiba with the same resolution as my my Inspiron 3558. I have used both of these for the last 6-7 years on this same TV as my home only monitor. Literally the next day I plugged in the 3558 and the screen keeps going black for a second or 2 and sometimes the resolution is adjusted higher than what I specified it be or lower sometimes. I just want it to stay at the resolution I set it at and not try to change it on me. But Indian Customer Support can't seem to grasp this no matter how I try to explain it. I was going to buy an extended warranty, but I'm not going to pay anything to have this happen when ever a problem comes up.