All the program settings of 4Spell are stored in a file called 4TEX.INI. Note that the file is not called 4SPELL.INI because 4Spell is a part of the 4TeX Workbench. 4Spell can run stand-alone, without the 4TeX workbench. The settings of 4Spell, however, will always be written in 4TEX.INI
The first time you start 4Spell all the necessary default entries are generated. Every time you quit 4Spell all the current settings are written to 4TEX.INI.
When selecting a new format, the new entries for the format are stored in the INI file. You can edit 4TEX.INI file with any ASCII editor. However, almost all options and settings can be changed from within 4Spell.
In case you want to use a different INI file for a special purpose, you can supply the INI file as a command line parameter.