ANSWER:
Not all shayateen are chained. Only the leaders or the strong ones are chained, which means they could not do in Ramadan the things they used to do throughout the year. Let it also be known to you that alqareen, who is the resident shaytan, never leaves you no matter where you go. Also there is the evil within every one of us. Therefor, all of these factors promote the evil which we see during Ramadan, yet it is certainly less than outside Ramadan.