There is no way to do the thing you are attempting. The .fsb (or "FMOD Sound Bank) file format is not designed to be edited or viewed by end users.
To begin with, it is a ‘built’ format, meaning that it cannot be opened and edited as you would a document; Rather, you would need access to use original .fdp (“FMOD Designer Project”) file, as well as all the audio files used to create that project, to build new versions of each .fsb file you wanted to replace.
Many game developers do not want end users to have ready access to their audio assets, and do not intentionally make their assets available. To this end, we do not create or distribute tools that could be used to extract the content from .fsb files. In addition, FMOD Designer allows developers to encrypt their bank files; Developers can make use of this feature to prevent .fsb files from being opened with even third-party tools.
Thus, if you want to edit the .fsb files of a game, you must contact that game’s developer and ask them for legal permission, the game’s original audio assets, the Designer project files they used, and any encryption key used for that project.
If you do obtain the permission and files required, you will need to use FMOD Designer, rather than FMOD Studio, to build the new .fsb files. FMOD Studio banks use the newer “.bank” format.