Caregiver gets angry at other residents at my Mom's personal care home. What is the next step we should take?

My mom just moved into a new personal care home last week, she was actually the first resident. There are now three other residents there. My mom tells me that the caregiver yells at the other residents all the time. It can be 8pm and they are in the living room area and she yells at them to get back into their rooms and go to bed. She yells at them if they sit at the dining room table while she is cooking dinner (I have observed that myself). She yells at them to clear their table, instead of just asking. My mom does not get yelled at herself. The other woman are much older than her and typically sleep in their rooms all day. My mom is younger than the average personal in a care home, she is 67, she's there because of her MS.

My mom has told the manager of the home about this and it seems he has done nothing about it. What is the next step we should take? Observing her with my mom, she is very good with my mom, maybe a little lazy if anything but she does her job.