Garmin 74C 用户手册

You can use the Audio menu to adjust the sound volume and select 
the audio input port.

1. Press the 

Menu

 button. You see the main menu.

2. Select the Audio menu. You see the following:

3. To increase or decrease the sound, select 

Volume

 and use the 

directional buttons to adjust it.

4. If you’re using a different audio input port than the default port 

for your source, select 

Audio Input

 and then either 

Audio 1

 or 

Audio 2

. Then press 

Enter

.

5. When you’re finished adjusting the audio settings, press 

Esc 

or 

Menu

.