Was and were

Both was and were are the past tense of the verb  “to be“. WAS, however, can be used only with the first and third person singular, i.e. I, he, she, it, while WERE can be used with the rest of the pronoun  i.e. you, we, they.

For instance, if you are talking about only one person, use was, e.g. “James was my friend at high school”. 

If you are talking about more than one person or addressing someone, use were, e.g. “James and I were friends at high school”“You were friends with James at high school”.