I'm a fourth year student

Because your friend is still right, even though the discussion has come to an end.

You should have presented the post as intelligibly, clearly and grammatically as possible. See the modified version of your question:

My friend and I were discussing some topic. As we closed our discussion, I realized that he was right in his arguments. So I said, “You were right”. Then my friend told me that I should use the present tense and say, “You are right”.

The discussion had ended five minutes before I said it. Then why should I use the present tense? I am confused. Please guide me.

Now the answer given by Bev clarifies the position.

Sir, why should I use the present tense not past tense?

Have you considered that perhaps he did so, as well as he possibly could?

Because your friend is STILL right (in the present) even though the discussion ended in the recent past.

The further back in the past the discussion took place, the more likely it is that you would use the past tense. However, when the discussion took place recently, even though it is now completely finished, the present tense can be used.

You should use the present tense because your friend is still right, even though the discussion has come to an end, as Beeesneees (Bev, as some of us call her) has said.

Now, suppose you want to tell another friend (of yours) about the outcome of the discussion you had had with him (your first friend), then you would say like this: We had a discussion on some topic. He was arguing on a particular point. I could not agree with him until he substantiated his contention quoting official statistics. Then, of course, I had to agree to what he had said. As I realized that I was wrong, I told him that he was right. (Here you can use the past tense)

I was trying to make the poster, an Indian, understand the difference between the two versions though we were able to grasp what he/she (they?) wanted to convey.

That’s not what your statement implies when you use ‘you should have…’. There is a clear indication here that you expect the poster to have presented the post in a different way.

It would have been better stated:
“Here is your post presented more clearly and grammatically:”

Yes I do.

Well, you are not consistent with your responses. When you point out ‘u’ as not being a word in existence, you often forget to correct more serious errors such as the ones you would find in the original post repeated below:

e.g me and mine friend were doing discussion on some topic. As we got the solution of our discussion . I said , " you was right “. Then my friend replied you should use present tense and the correct sentence is ,” you are right".

Do you mean to say that the poster need not be corrected in the above case? We are on this forum to discuss and learn English, not to unnecessarily criticize or even to teach others. What we say may be accepted or rejected.

I take liberty with many of the users and explain what I know in more detail, and tell them that they should have done like this or that since they have already become my friends via private message facility or email. I enjoy being in touch with them. So do they, I believe.

No THL, I don’t ‘forget’ to point out serious errors.
When I point out the basics, I consider them to BE the ‘serious’ errors! They are the over-riding uses that we come across every day, and if they cannot get those correct, then the rest will never fall into place.

If I were to point out every single error in a learners’ post the over-riding effect would be likely to be a total sense of failure for that student. Modern research into the learning of second languages backs up my viewpoint on that. Learners need to be encouraged and my way of doing so is to focus on one or two basics at a time, not to expect them to get everything right straight off.

So I was right in my first assumption that you had not considered that perhaps he presented the post as well as he possibly could.

Be that as it may. I have known you online for more than two years now, Bev. I do not want to lock horns with you, anyway. I hope you will appreciate it when I say that I know the pulse of my own countrymen more than you do.

Sorry THL, but I find that far too much of a generalisation to accept. I would never assume to claim to know everyone in my own country that well, and don’t see how you can.

However, we will have to agree to differ as I have no wish to ‘lock horns’ with you either and it is obvious that we both have our own opinions - and I’m sure you’ll agree that ultimately there is absolutely nothing wrong in that!