Why we use were with you

These words are used differently in sentences, so it's important to know when to?use were?vs.?was.?Was?is used in the first and third person singular past. It is used for statements of fact.?Were?is used in the second person singular and plural and first and third person plural.

Because you is plural either it is in present or past tense.

because the word is plural either with present or past tense

Because were and was are past.
If you need to describe past you can use were and was.
But were is plural.
And was is singular.

I was
You were
He was
She was
It was
We were
Your were
They were.

Were is past tense ant it is plural you is also plural