We all have different personalities, we have some people who are jovial and friendly and some who love to be themself, but keeping a straight face makes people fear or judgment. Have been told by my friends that some of my coursemates want to be friends with me but because of my personality they can't come to me. The reason why they didn't come is that don't associate me with people like that and I do keep a straight face but if you see me laughing it means that am with my friends. But you can try and adjust your personality.