There is no difference between you (singular) and you (plural) when it comes to tenses:
Present Simple:
- You are a good friend.
- You are very good friends.(plural)
Past Simple:
- You were a fit guy 2 years ago.
- You were very fit 2 years ago.(plural)
Future Simple
- You will call me tomorrow.(singular or plural depending on the context)
So, you use them in the same way, but the only way to understand if it’s plural or singular is context.
I hope this helps 🙂
Read more:
List of Words Without Plural Form (Uncountable Nouns)
Collective Nouns
Is there plural for “Staff”?