If you upload a file to the hit sounds you're not able to change them later. It says it has been successfully changed but it doesn't actually change it. Not tripping out too bad because hit sounds are cheap but this should be fixed.
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Is there anyway you guys could reset the sounds so I can change them??
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Nevermind don't reset the sounds, I just sold the old ones and bought new ones.

So... For future I am pretty sure your problem was having to do with your custom folder. A couple of items textures/sounds will stay in your folder even after you sell/change them. The way to fix this, is to search your custom folder on your computer. Once you have found it, delete everything (or just the stuff that you changed). Then, go In-game and type /dl (your username)

This should fix it!