Difficulty appearing 'sure of myself' confrontational situations... please help?

I do that, too. I think it's a confidence issue. You just need to ure yourself that you're smart. Throughout the day, if you find yourself doubting your intellegence, calm yourself down and tell youyou've that you're smart and you will understand this.. or you don't look dumb... or that you're only human. When you start to doubt yourself or think that someone is arguing with you, just tell yourself that you've got this and congratulate yourself on small things.