Canon EOS 5D Mark III Instruction Manual (en)

If you press the <o>, <n>, <m>, <S>, or <b> 
button while the image is displayed on the LCD monitor, the setting 
screen will appear on the LCD monitor and you can turn the <6> or 
<5> dial to set the respective function.
When f is set, you can press the <S> button to select the AF area 
selection mode and AF point. The procedure is the same as with 
viewfinder shooting. During manual-exposure shooting (p.225), you can 
press the <m> button to set the ISO speed.
Note that the following cannot be set: <q> Metering mode, <y> 
Flash exposure compensation, <
w> HDR mode, and <P> Multiple 
While the image is displayed on the LCD monitor, you can press the 
<Q> button and set the following: Auto Lighting Optimizer, card 
selection, recording function, image-recording quality (still photos), 
movie-recording size, and sound-recording level (with [Sound 
recording: Manual
] set).
 Press the <Q> button.
The settable functions will be displayed.
 Select a function and set it.
Use <
9> to select a function.
The setting of the selected function is displayed at the bottom.
Turn the <5> or <6> dial to set it.
To set the card selection or recording function, press <
0>, then
turn the <5> or <6> dial to set it.
Shooting Function Settings
 / R / B / i / S / A  Settings
Q Quick Control
During movie shooting, you can set the following: Shutter speed, aperture, 
ISO speed, exposure compensation, and sound-recording level. (Settable 
functions may differ depending on the shooting mode and [Sound 
] setting.)