i used to just replace the sound files but now that i've reinstalled i absolutely cannot find the sound files anywhere in my folder. sorry for the dumb question but i've seriously looked for an hour for these files to replace.
use https://osu.ppy.sh/wiki/Skin for file names and add appropriate hitsounds to your active skin (normal-hitnormal.wav, etc, etc) if you use default skin, create an empty folder called something something in Skins directory and put audio files in it, then select it as your new skin in settings