Learn Italian: Anche l'approccio operativo è cambiato. - The operational approach has changed too.

Cambiare is a verb that can take either auxiliary depending on how it is used. When a subject changes something else (like "I changed my mind"), you use avere. But when the subject undergoes the change itself, without a direct object (like "the approach changed"), you use essere.

Since we used essere, does cambiato have to agree with the subject?

Exactly. Whenever essere is the helping verb, the past participle must match the subject in gender and number. Since l'approccio is masculine singular, the participle is cambiato. If the subject were feminine, like la situazione, it would be è cambiata.

Because it uses l', how can I easily tell that approccio is masculine?

While l' just tells you the noun starts with a vowel, you can look at the end of the noun itself: it ends in -o, which usually indicates a masculine word. You can also spot the masculine -o endings on the adjective modifying it (operativo) and the past participle (cambiato).

Why does the adjective operativo come after approccio?

In Italian, adjectives that categorize or define a specific type of something—like pointing out this is the operational approach rather than a theoretical one—almost always go after the noun.