People say they can’t tell when I’m being sarcastic or not

Apparently I have an extremely sarcastic voice and I say everything with the same voice. So people I know say that I can be bitchy about stuff when I’m not even trying to be. To be completely honest, I can be a bit of a mean person sometimes without realizing that I am. To me, what is a sarcastic joke is to someone else being super rude. I genuinely don’t know how to fix this since this literally just the way I talk. Help?