i'm a chinese.about the question of you。可是 and 却 are very similar in the meaning。but，there is some difference in the emotion of them。
such as
我认为这是对的，可是你不这么认为
我认为这是对的，你却不这么认为
我认为这是对的，可是你却不这么认为
the emotion of stress about “你（you）”，become more and more heavy。

if you have any other questions about chinese.my email 782597034@qq.com