Now hear me out, we are all different individuals, which is a very good thing, keeping us all unique from each others, now read that again.
That's the "issue", since we are all unique in our own ways, it means we all had different circumstances which make us think in different ways, so communicate your thoughts very clearly in order to be understood.
Easy as that, there is no magic trick to it or anything, of course we should pick our words carefully to not hurt people or be too harsh on them.
Nevertheless, that's only 50% of the communication, because if the second part doesn't want to understand then you can't do much about it, yes i said doesn't want to understand, because if the communication is clear there is no way they "can't" understand it.