Can landlord change his mind 2 weeks before signed agreement kicks in?

My apartment was sold in September. I was month to month. With the new owner, I signed a Notice of Change in Terms of Tenancy stating that my lease would change from month to month to one year beginning December 1. Two weeks before that date, they now want to stay month to month. I believe the Notice of Change in Terms of Tenancy is a binding addendum to my old lease. Can they change their minds two weeks before it converts to a one-year lease? I'm afraid to try to hold them to the agreement. If I refuse to sign, I don't know if they can still give me 60-day notice to quit while I'm still month to month.