Take a look at this article; it describes a technique to effectively randomize the presented order of an arbitrary number of questions: Randomizing the order of questions - Showcase - ODK Forum
BTW, if you have fewer questions, eg only 2 or 3, or it doesn’t need to be truly random (eg perhaps not all possible permutations are displayable…) then there are somewhat simpler approaches. But the above will handle the general case.
