How can I make my own sound modification?

I know there is a “guide” but it doesn’t work, at least for me.

What I did:

Downloaded someone else’s mod. (To have file names)
Opened via Fmod Bank Tools
Edited the file, replacing the main menu music, WAV format
Named the replaced file as it was, enlisted_theme_01.wav.
Used the rebuild command
inserted the BANK back into the mods, the result is that the music remains from the old mod OR the standard music plays.
And what did I do wrong? I pre-converted the files to wav, named them as they were, so why is the music from the old mod after the rebuild?

maybe @Bigote0070 can help

A large can of baked beans, and you’re done.