A signal processing apparatus includes: a memory, a signal processor, and a microcomputer. The memory stores a setting file including: a common portion that holds at least one common parameter that is used in common for functions performed by the signal processing apparatus; individual portions that each individually hold parameters; and a changer that holds change information to change the at least one common parameter. The microcomputer (a) reads the common portion and the individual portions from the memory, and sends the read portions to the signal processor, and (b) selects one of the functions, and controls the signal processor in accordance with the selected function and the change information so that the signal processor uses i) the parameter in the individual portion corresponding to the selected function, and ii) the at least one common parameter of the common portion that has been changed based on the change information.