Updated February 10, 2017 Click the “Apple” logo at the upper left and click “System Preferences” to launch System Preferences. Click “Sound” in the “Hardware” section to launch the “Sound” dialog box. Click the “Output” button if you want to increase the volume of all sounds played through your iMac’s speakers. Drag the “Output Volume” slider to the right to make your iMac’s speakers louder. Move the slider all the way to the right if you want to maximize the volume.
