The past tense of are is were. Use it for earlier times, with you, we, or they. With I, he, or she, use was instead.
We were at the park all afternoon. You were right about the traffic.
The past tense of are is were. Use it for earlier times, with you, we, or they. With I, he, or she, use was instead.
We were at the park all afternoon. You were right about the traffic.
So whenever you talk about something that already happened and the subject is we, you, or they, were is the form that fits, as in They were tired after the trip.
One nearby form to keep straight: with I, he, or she, the past tense word is was, not were. So I was tired and He was tired, but You were tired and They were tired. Both words sit in the same past-tense slot; the subject decides which one you pick.