If there is more than one clause in a sentence, you have to specify which one you're talking about.
In He causes you difficulty, the main clause has he as subject, causes as verb, and
a direct object composed of a infinitive clause something like (for) you (to have) difficulty.
This clause gets ground down by deleting to have (note that you can put it back again, so this is an optional transformation), and by undergoing Subject-Raising, which loses the for and promotes the downstairs subject you to become the upstairs direct object of cause; this can now be passivized and become an upstairs subject, for instance: You were caused considerable difficulty by him.
But you isn't really part of the main clause; it starts out only as the subject of the complement clause and just gets put upstairs by Raising. You can tell this by looking at idiom chunks that get displaced from their ordinary sites, like dummy there and the cat below:
- They believe [there to be a party tonight]. ==> [There] is believed [to be a party tonight].
- They consider [the cat to be out of the bag]. ==> [The cat] is considered [to be out of the bag].
Raising moves a noun phrase to object status, and it then behaves like an object (e.g, passive applies); but raised objects don't have any semantic object relation with their verb. If he causes you to have trouble, he doesn't cause you; the causation has to do with a clause, not a person. If they consider you a genius, they're not considering you; they're considering a proposition about you. And so on.
Most important, distinguish complex sentences from clauses. You can only talk about subjects and object of individual clauses.