Observation matters in sub-atomic physics because you can only look at a particle by bouncing another particle off of it, and that changes the particle you are observing. We are accustomed, in the macroscopic world, to thinking that looking at things does not change them, but that is only because large objects are not usually changed significantly by the tiny photons that we bounce off them. With sub-atomic particles, observation necessarily changes things.

But that does not mean that all things are in some kind of state of suspension until we observe them. The universe functions even when no one is watching. Observation is not a magical force in our universe that makes everything happen. Uranium atoms are going to decay, according to a well established statistical rate, whether anyone is looking at them or not. It does get harder to predict, the few atoms are involved, since you lose the statistical averaging effect.

In a certain sense, particles do act in accordance with our choices, and that is just as true on a macroscopic level as on a sub-atomic level. If I decide to drink a glass of water, then all the sub-atomic particles which constitute that water are going to change their locations accordingly, and enter my body. In that sense, there is no question that I make decisions and that my decisions affect the physical universe. The interesting question would be, why do I make those decisions? Am I really free to decide things of my own free will, or do I inevitably make the decisions that result from all the influences that act upon me? That is much harder to say.

I mention quantum mechanics mostly because there are still a lot of questions about exactly how quantum mechanics works. It is a very complex and partially understood branch of theoretical physics. Given the way in which events are described by probabilities in quantum mechanics, rather than as definite events as classical mechanics does, there may be some way in which a given circumstance could lead to more than one possible outcome. But that has not really been established, it is still quite speculative. Even when events are described in terms of probabilities, they may still lead to just one unavoidable outcome.