The study aims to examine the validity of 2D and 3D applications for online learning of playing the piano and music theory related to self-efficacy. We shall consider the effectiveness of replacing a piano/music theory teacher with online courses on a device, taking into account both advantages and disadvantages. Self-efficacy in online piano training is deeply layered, considering multiple elements, such as genre, coverage of music theory, system of musical notation, repertoire, finger technique, teacher feedback, cost, interactivity, resources, difficulty level, pros and cons of self-learning and many other related aspects interconnected to the main concepts of Albert Bandura. The article considers analysing the most popular applications for self-directed piano and music theory learning, using devices such as smartphone, tablet, laptop and also the effectiveness of using VR equipment for a complex immersive experience. The high-tech expansion has led to developed self-efficacy strategies that aim at learning music fast, through specific applications, frequently using mixed reality. In addition to the provided information, we shall express limitations regarding the applicability of this technological system of learning a new music skill.