Question

in science, a hypothesis must be true.

Answer 1

no, in science your hypothesis does not have to be true. A hypothesis is just what you think your outcome will be. if you turn out to be wrong then you can always go back and do more research and create new hypothesis :)

Answer 2

You don't necessarily have to change you hypothesis. You will still learn the right answer in the end :) If your hypothesis is proven false, you will learn that the answer is exactly the opposite of what you thought, so you still win! :)