What @Trung describes is not possible in ODK and does not sound convenient for a small number of questions to randomize. The recommended strategy is similar but within a single form.
You can create groups for each order that you might want to display to the user, generate a random number, and use that random number to pick one of the orderings. Here is a form that shows the strategy with two questions. Note that a dynamic default is used to ensure that the random value is stable across multiple opens of the same form instance.
There has been some discussion of adding a dedicated feature for this purpose at Randomizing Lists or Questions within Groups.