Were has a lot of rules. It is used second person (you) singular "Maria, you were totally right about Joan" It is also used in both first (we), second (you) and third (they) plural It is also used in what is called simple imperfect subjunctive in all persons of be. Ie. I wish that it were Sunday. or I wish that I were with you. The second one is a bit more complicated, but if you want to make it simpler, just use the first rule, that's fine aswell. I usually remember it in list form I was, you were, he/she/it was, we were, you were, they were.