I used to have pretty severe social anxiety disorder. And like you, many people thought I was aloof and arrogant, when in reality, I wasn't quite sure how to act or what to say. At some point I learned a smile and some short, simple conversation can go a long way. It helps to genuinely not care what other people think of you—it took me a few years to get there. I’m not suggesting intentionally alienating people, but a lot of us really take a disapproving word or look to heart and let it change our whole mood and perspective--there's no need to do that; we can never please everyone.