Why doesn't full screen mode stretch content on some monitors

I am new to Unity and working on a 2D game for Mac/Win and have found that the game WILL stretch content to fit on my notebook computer monitor but WILL NOT stretch content on a connected 1080p TV/Monitor when it is used as the primary monitor (notebook closed). The content WILL NOT stretch on a Mac Mini with a connected 1080p TV/Monitor either.

When the game is in full screen mode it uses the full screen but maintains the 4:3 aspect ratio of the content. I would like it to stretch the content.

  1. Make sure you only allow the size 16:9 in the Build Setting.
  2. When running the game, try different Graphic qualities.
    For example, when I run my game at 1024 x 768, it steches out. But when I run it on 1366 x 768, it fits my screen.