Want to play with English Audio & Spanish Sub

[Ra-Sho-Mon]

Hello I'm playing FONV and it was in Spanish. I prefer to play with English audio and Spanish subtitle/menu/option.

How could I make that? I'll appreciate the Help. Thank You!

[Belanos]

You'd need to use the English version of the game and translate all the subtitles and menus to Spanish yourself. There's no way to mix and match languages in the game itself.

[JDC UK]

A little googling suggests it's possible to swap the BSAs.

1) Download the English version.
2) Keep copies of all BSA files.
3) Download Spanish version.
4) Replace Spanish BSAs with the English ones. Keep copies just in case it doesn't work.

For just the main game you should only need to replace "Fallout - Voices1.bsa"
And for the DLC you'll need to replace the "Main.BSA" for each of them.
I have no idea if the other BSAs are necessary, but you should keep copies of all of them in case you do need them.