This is a bit tricky and not something Duolingo explains very well. In Spanish historia can be used to refer to both a history in the formal sense we use it in English, as a subject, or a story about real events told in a narrative format. Cuento and historia are similar, but not interchangeable words. Cuento specifically refers to a fictional story, while a historia at least has the premise of being something that actually happened.
Well, first it would be cuentos (masculine) for stories. Cuentas (feminine) is used for things involving sums (bank accounts, restaurant bills, mathematical calculations).
Edit: Also keep in mind that contar conjugates to cuentas for the second person present indicative.
With that distinction, typically historia is a factual story (non-fiction), whereas cuento is a fictitious story (a tale -- fiction)
Since I don't see a good answer to this question I'm posting it. If the intent of this sentence is 'They have a good history' then that should be accepted as a correct answer despite the fact that 'historias' is plural. I would like a native speaker input on if this is how it is actually said or not.. i.e. plural and not singular like in English.