Located on the bottom left corner of the home screen of your Atomos device you will see the Audio panel and quick headphone volume adjustment bar.
To adjust the headphone volume slide the volume adjustment bar accordingly
For complete audio setup, tap the audio bars to bring up the audio settings panel. From this panel you can assign the channels that are being recorded, assign the channels that are being monitored using the headphone jack and make more detailed audio adjustments (settings available vary by model). The number of audio channels available to monitor and record will be dependent on the Atomos device you are using and the audio signal itself. For example, over HDMI a Ninja2 can record 2ch whereas a Shogun Flame can record up to 8ch. You can check specifications at atomos.com and select your product of choice. The digital audio channels for selection are on the left hand side of the audio settings panel and the analogue audio channels are on the right hand side.
Each channel has a level meter assigned to Left & Right Channels. When there is an active audio feed you will see the level indicator moving. You can choose to record from any or all of the active digital (SDI or HDMI) channels as well as analogue inputs. Adjacent to each pair of audio channels you can see the record button, when this is shown in red it is set to record, simply select the channels you want to record. To monitor the audio, tap the headphone icon next to the channel you wish to monitor from the headphone output.
Selecting the Monitor icon does not mean that track is selected to be recorded. You need to select each channel using the record button. Tracks that are selected to be recorded have colored Audio Meters.
Figure 1 - Audio settings panel (Shogun, Assassin, Flame and Inferno series)
Figure 2 - Audio settings panel (Blade and Ninja2 series)