According to the MWI (which is not "prevailing quantum theory") all outcomes of QM experiments are realized, but the experimental apparatus and the rest of the macro world around it become entangled with a particular outcome, and thus unable to perceive the other outcomes.

So after every quantum experiment you get N copies of the world, one in which outcome A has happened, one in which B has happened, one in which outcome C has happened etc, and each of these evolves divergently from there on. Of course, there are trillions of trillions of trillions of "quantum experiments" happening in our immediate surrounding every second, so any one experiment in particular is not that important, but it helps to isolate.

So, instead of taking a decision, you use the app to rest easy that somewhere out there in the universal wave function, there is a copy of you that has taken the opposite decision.