Answer 1
This means that if you make a negative remark, they will obsess over that flaw.
answer 2
If you’re constantly teasing a friend, or your little sister, because they’re short, or chubby, or not as smart as you, or not as knowledgeable as you about something… you can “give them a complex.” , meaning an inferiority complex, or the belief that they are too big, or too small, or too stupid to be much.
answer 3
It means someone is so upset about something you did that they think that way of you in most circumstances. For example, Hitler enslaved the Jews and created the Holocost. Many Germans are considered anti-Semites. It’s a complex.
answer 4
means the person is not wise enough to realize that they are letting someone play with them
Answer 5
make them paranoid by making them believe that their something is not.