Just in case there's any confusion about what that self-explanatory camera mode switch does on the HTC EVO 3D, Radio Shack has included a brief explanation on how to turn 3D on or off on the phone's new page on its website.
Contrary to what a few sites reported during the EVO 3D's official unveiling in March, the metal switch on the bottom right side of the phone is exclusively for the camera: you slide it to "2D" to take pictures in 2D mode and "3D" to take pictures in 3D mode. That's why it's called the camera mode switch. It does not control any of the 3D elements on screen.
As stated on the Shack's site, 2D and 3D content are automatically displayed. When a 3D-supporting video, app, or game is opened, the screen will automatically display it in 3D. When 3D content is not detected, it will "fall back" to 2D. I know some people were thinking that they'd be able to control when they wanted to see their content in 3D, but this isn't how it works.
The EVO 3D will always display 3D content in 3D and 2D content in 2D. So if your eyes are going crazy from some insane 3D action, it seems you're either going to have to deal with it or just not view the content anymore.[Radio Shack]