Each plug-in window contains controls to adjust the values of the parameters for that plug-in. Some controls, such as buttons, knobs, and sliders, are shared by different plug-ins, while others are unique to a particular plug-in. Most controls are labeled to show the parameter they affect. Full details on the parameters of each individual plug-in can be found in the Logic Pro Instruments and Logic Pro Effects manuals.
Do any of the following:
Click buttons to switch them on or off.
Drag knobs vertically to adjust their value.
Drag sliders horizontally or vertically, depending on their orientation.
Enter a value in a numbered field.
Select a control, then move your mouse wheel or swipe your trackpad to adjust the value.
Option-click the parameter.
Hold down the Shift key before manipulating a control.