Bulk Rename Utility

I don't want to go in each folder and rename the files, can't I just select folders and rename the files inside them? When I tried to do that, it changed the folder's extension. Here's an example on what I mean:
[Folder] -[Folder] - [file]
---------------------- [file]
---------------------- [file]
----------[Folder] - [Folder] - [file]
--------------------------------- [file]

I only want to rename the files.

nvm I figured it out