My boss is a twat. In person I kind of like him. He's funny and sarcastic which makes me laugh. But online he has the worst tone ever. He says dick things to his female colleagues - talking about taking us all back to school because we don't understand his messages. Sharing criticism of our work on shared documents so anyone can see his comments, telling us our work is poor, he has to spoon feed us, we don't listen... a bunch of other stuff all delivered in a way that's not constructive and makes us feel shit. Yesterday he spent five minutes yelling at me on a call. Today a colleague said he was messaging her all in caps and complaining that she doesn't listen.
Anyway I've suggested we take it to HR but I'm new in the company and not 100% sure of what's the appropriate approach. Should we take our complaint to him first, or should we take it to his line manager, or do we raise it with HR? Thanks.