Why do people assume I’m angry?

The best advice I can give you is to ignore what other people think about you at work. Very often people make wrong assumptions about people they know little or nothing about. And look where you are by being concerned about what they are thinking. In your own words " I’m very confused". And the next time the person that told you this useless information comes to you to share what others think about you tell them you really don't care to hear it!

Seems like you have to write those words in a conspicuous place, at work somewhere. Or not...but you can't cater to shallow, empty people. That can't be the way everyone feels. I'm the same way. All you can do is be yourself.