Since horror games are generally not accepted on Scratch, I plan on releasing mine on seperate site, or maybe even on an app store or something. But the horror game uses disorted versions of some Scratch sound effects, could I still use those sounds? If so, who do I need to credit if I do need to credit anybody

No, most of them are trademarked by ST.
read what Kessel_Run said

Scratch assets (except the copyrighted ones- think Scratch Cat, Gobo, etc) are licensed under the Creative Commons Attribution-ShareAlike 2.0 license, which requires that you attribute any material you use to the original author. Probably just credit the assets to scratch.mit.edu. However, all the sound assets on Scratch come from free-resource websites. From the Credits page:

Scratch Team said:
The Scratch sound library uses free sound resources from Adobe.com, Archive.org, FreeMusicArchive.org, FreeSound.org, and Incompetech.com.

Thanks to Nina Paley from Archive.org; Kellee Maize, Peter Rudenko, and Chris Zabriskie from FreeMusicArchive.org; and Kevin MacLeod from Incompetech.com. Thanks to the following freesound.org artists: acclivity, belloisec, Benboncan, Calcuttan, coby12388, copyc4t, cs272, Flick3r, FreqMan, gelo_papas, han1, InspectorJ, jiserte, junggle, juskiddink, klankbeeld, LittleRobotSoundFactory, LloydEvans09, lonemonk, rhodesmas, sandyrb, themfish, tyops.

So if you're just releasing the game on a personal website, you probably don't have to worry about any of this, but if you plan on selling it on the App Store it might be good to credit either scratch.mit.edu or the people that the ST credits.