Это формы глагола to be для Past Simple
was только для единственного числа, а were - для множественного (после you всегда следует глагол в форме множественного числа).
(+) I was happy. He was sad. She was pleased. It was great.
(-) I wasn't interested. He/she wasn't surprised. It wasn't funny.
(?) Was I/he/she happy? Was it a great idea?
(+) We were tired. You were angry. They were surprised.
(-) We/you/they weren't tired.
(?) Were we/you/they glad?