You can update your system using several methods provided by Official PlayStation Support :
The release of the is a significant milestone for Sony's beloved handheld, as it represents the first system software update in years . While the update aims to modernize account security, it also introduces several functional changes that every Vita owner should know about. What's New in PS Vita Firmware 3.74? ps vita 374 firmware new
: Traditional PSN passwords no longer work for direct login on the handheld. Users must generate a unique "Device Setup Password" via their PC or mobile browser to sign in. You can update your system using several methods