Is it necessary for you to change script once it works ?
Further, if you wish to keep type of font and color as chosen, you can select "Save subtitle font settings" on "Subtitles"-tab of "Options"/"Preferences".
(I personally would advise to also check "Use outline font").
You don't necessarily need ini (bsi) files.
If you do want to use inifiles, why don't you have a look if Matimott's Inimaker isn't an easy utility for you? (See item 7 of
Help to Help hereunder)