A control object among control objects is assigned to each of a plurality of channel strips each have at least a control and are disposed on a panel according to a predetermined order. A parameter of control object assigned to each channel strip is adjusted in accordance with a manipulation of the control of the channel strip. A display unit is controlled to display parameters of the control objects assigned to a series of channel strips extracted from the channel strips arranged on the panel according to the order, and on accepting a first operation from the user, another series of channel strips are extracted from the channel strips, and the display unit is controlled to display parameters of the control objects assigned to the extracted channel strips.