subject-verb agreement

People have behaved really excited at a time when I went to London last summer. I think they were excited because I didn't see them for a long time, and they didn't see me for a long time either. I also think they were really excited because I came from the US. And that they came from London, so that they wanted to know much about me as possible.I was really happy to when I saw them. Cause I missed them so much. And allot of my cousins were there.