We can change the current OpenGL version by creating a QGLFormat object and calling QGLFormat::setVersion, then passing the format into the QGLWidget's contructor.
NOTE: OpenGL 3.3 is being shown on my current machine with an ATI Radeon HD 2400 Pro graphics card. However, setting the version to 3.2 will give out a lot of warnings and nothing is being drawn on the screen. Setting the version to any versions between 1.x and 2.x will end up with version 3.3. The only version that I can successfully set to is 3.0 only.