Canon PowerShot SX400 IS Black Manual (en)

Regardless of the option selected in this setting, shots may be 
numbered consecutively after the last number of existing images 
on newly inserted memory cards. To start saving shots from 0001, 
use an empty (or formatted (
on the card folder structure and image formats.
Date-Based Image Storage
Instead of saving images in folders created each month, you can 
have the camera create folders each day you shoot to store shots 
taken that day.
Choose [Create Folder], and then 
choose [Daily].
Images will now be saved in 
folders created on the shooting