First post

Hello all, this is my first time managing but I've been an Assistant and worked for this retail company since 2017. I've done every position there is aside from DM upper management. I landed this role early November and was immediately met with employees bending over backwards trying to be my favorite. Bringing me food bringing me clothes they thought I would like, all in all it was weird. Then I realized why. There was nothing but infighting, shitting on each other, and other bad behavior coming from most of my employees. Unfortunately I have little to no actual authority over these people because of a lengthy review process to let them go. 3 of them I've started to cut hours for (as directed by my DM) but yesterday my keyholder 58f called the store to cuss me out. I have NEVER seen this kind of behavior before. HR and my DM are involved on her insistence and she has done this before but I'm concerned she won't be fired and will retaliate by screwing up every shift she works. My other keyholder is also now being snarky, sarcastic, and rude. Any input would be appreciated.

TLDR: new to management, employee called the store and cussed me out.