Sony DSC-RX100M3 - Manual (Page 39)

[20] How to Use Confirming the operation method Confirming the operation method
Using the Fn (Function) button
You can register frequently used functions to the Fn (function) button and recall them while
shooting. Up to 12 frequently used functions can be registered to the Fn (Function) button.
1. Press the Fn button in shooting mode.
2. Select a function to be registered by pressing the up/down/left/right side of the control
wheel.
3. Set the desired setting by turning the control wheel or control ring.
Performing settings on the dedicated screen
Select the desired function in step 2, then press on the center of the control wheel.