If you tick the Maximise Quiz in Browser tick box this will ensure that the quiz expands to fill as much of the browser window as possible. Sometimes this stretching will distort the quality of a bitmap (jpeg/gif) style background and you may prefer to have the quiz always shown at its default resolution.
A lot of things can go wrong during a test. The power can get cut, hardware can fail, the browser can crash, the test taker can close the browser by mistake, the internet connection can go down, the whole internet can go down, the results server and backup server can fail.
By ticking this box you can ensure that if something goes wrong while a user is taking a test, they can just bring the test up again, and all their answers will still be there. The timer will be set at the correct value too.
The responses are saved locally in the browser every 10 seconds, and the responses are deleted when the user sucessfully exits the test. The only time you might not want to use this feature is if you're collecting sensitive information, and you don't want to have this information stored on the user's computer.
The feature also works in combination with randomization, so it'll bring up the correct pre-randomized version of the test when the user re-enters the quiz.