"I do not like scary stories."
Translation:Nie lubię strasznych historii.
I understand that you mean the 'puzzle' exercise. Well, it is based on the default sentence, which uses the word "historii". (in plural, although there's no difference between Genitive singular and Genitive plural of this word).
"historia" is a perfectly fine word for "a story", and this is the default answer. "opowieść" was accepted 9 months ago, but it's only accepted.