We often tend to say "I know" when people share or suggest something. While it is not the wrong thing to do, strangers who know little of your character might take it arrogance. In certain cases it will also show that you are being snobby or even paying less attention to the speaker.

Instead, you can convey the same feeling when you say "you're right". It will let the speaker think you are paying attention to them, listening to them while also telling them that you know what they are talking about without being a snob. Giving importance to the speaker in a talk will give him the impression that you value his speech and will move more closely with you.

(AW- Anil)