Learn Italian: Voleva uscire, ma ha dovuto rinunciare. - He wanted to go out, but he had to give up.

This sentence perfectly shows the difference in how these past tenses work with modal verbs (like wanting, having to, or being able to). Voleva (imperfetto) describes a past state or desire: he had the ongoing intention to go out. Ha dovuto (passato prossimo) describes a specific, completed event: a sudden obstacle arose, and he was forced to give up right then.

If the sentence used doveva instead of ha dovuto, would the meaning change?

Yes! If the sentence said doveva rinunciare (imperfetto), it would just mean he was supposed to give up, or had an ongoing obligation to, but we wouldn't know for sure if he actually did it. By using the passato prossimo (ha dovuto rinunciare), it tells us definitively that the action was completed: he actually gave up.

How do we know to use avere as the helping verb for ha dovuto?

When a modal verb is followed by an infinitive, it usually borrows the helping verb that the infinitive would normally use in the past tense. The verb rinunciare takes avere (for example, ho rinunciato), so the modal verb before it also takes avere, making it ha dovuto rinunciare.

Could voleva mean I wanted in this context?