No one can answer why people do this of that as we don’t know them.

But it’s perfectly fine to tell your boss to not yell or be rude. You don’t have to take abuse.

I’d not complain to HR though. They’ll look at it as you’ve been with this company less than a year and you’ve been getting into conflicts and problems with people: both clients and staff. So they’ll label it as your fault.

But talking directly to your immediate boss is very appropriate, maybe even in writing. They need to be respectful