Answer:
I don't think that the fastest way to change a word is to double click it. Even though it highlights it super fast, then you just press backspace once, it doesn't compare to the one where you press the "ctrl" and "backspace" key at the same time, and it makes the whole entire word disappear in the blink of an eye. But, I am not sure if anybody really knows about this trick. So, it is 50/50.
Step-by-step explanation:
:)