Here's what you do. Change your resolution setting back to how they were, you shouldn't need to change these settings. Now with the MackBook connected to the TV and both displays powered on go to the Apple menu> System Preferences> Displays. You'll notice a menu open on both displays. On the MacBook side near the top you'll see three options. Select the second one labeled Arrangement, in the window that opens check the checkbox that says 'Mirror Displays' and the TV will do just that and mirror your MacBook. Hope that helps.