Child Theme Question

When we make a change to a file in a parent theme, from my understanding we should be able to put that changed version in the child theme and that file should take precedence.

My question is do we have to create the same directory structure of the parent theme for that file to be placed in or can we just drop it into the main child directory.

I made changes to the parent theme and then thought I would have to do it all over with a theme update. I then researched child themes on WordPress codex and found you can indeed place files I the child theme.

However a change I made never took precedence so I am now wondering if I need to create the same structure - or if the change I made was just wrong and not working.