Modern nanotechnology allows the production of, depending on the application, various quantum nanostructures with selected properties. These properties are strongly influenced by the confinement potential which can be modified eg by electrical gating. In this paper, we analyze a nanostructure composed of a quantum dot surrounded by a quantum ring. We show that, depending on the details of the confining potential, the electron wave functions can be located in different parts of the structure. Since many properties of such a nanostructure strongly depend on the distribution of the wave functions, by varying the applied gate voltage one can easily control them. In particular, we illustrate the high controllability of the nanostructure by demonstrating how its coherent, optical and conducting properties can be drastically changed by a small modification of the confining potential.