Put the .INI into
users\%USERPROFILE%\Documents\My Games\BioShock Infinite\XGame\Config\
or
Windows 11 or Latest builds of Windows 10 be on
OneDrive\Documents\My Games\BioShock Infinite\XGame\Config\
Just a faster way of BioShock Infinite - Tweak Guide
Put the file into
users\%USERPROFILE%\Documents\My Games\BioShock Infinite\XGame\Config\