And the we find out by phone she his putting the apartment on the market

She can sell anytime she wants, it does not alter your lease. The new owners have to accept your lease as is but can change it when it expires kicking you out or raising the rate at that time

And your question is what ?

They can always sell the apartments, the new owner will be obligated to honor any lease in place.

And the property belongs to them, so they may upgrade if they wish.

What disadvange or problem has this upgrade caused you ?