I was hired to be weekend supervisor, but due to another job commitment I would need every 3rd weekend off. This was agreed to. After 2 weeks into the position, Manager was let go and an interim Manager came, well 2 of them, they would work alternate 2 we

hired as the weekend supervisor with every 3rd off. now the new manager is stating I am not meeting commitment. I feel they have already offered my position to another co-worker which was denied my position and wanting me to go to floor staff, which I do not want to. As long as your shift is covered, they did not care about staff taking off. Now due to the co-worker I had made agreements to cover my shifts, They pulled the co-worker from staffing mix and stated due to me not working my shifts, they had to scramble to cover. Also stating I am not consistent and staff does not feel they could come to me for help. Which I am just now hearing about. Which I wasn't given names of who feels this way. When I worked as agency their, staff came to me all the time for questions. Now I am being told that they don't feel they can come to me. So, I guess my question is, knowing that I was hired to work weekends with every 3rd weekend off, can they force me into another position or quit?