Was and Were

If in the present simple, the verb to be has three forms (am, is, are), in the simple past, it has two: was and were.

"Was" corresponds to: I    She    He    It

"Were" corresponds to: You   They     We

•The affirmative structure is:
  Pronoun + Was/Were + Verb
For example: "I was in the house"
                         "We were eating in a restaurant"

•The negative structure is:
 Pronoun + Was/Were + not + verb
For example: "I was not in the house"
                         "We were not eating in the restaurant"

•The interrogative structure is:
 Was/Were + pronoun + verb
For example: Was she a doctor?
                         Were you at work?

For more information:

https://www.grammarly.com/blog/was-vs-were/

https://youtu.be/GKF6IiNa10U