As a number of previous contributors have pointed out you should not overwater your Yucca plant.
I have a theory that many 'housekeepers'(male and female)tend to kill houseplants because they make watering them part of their regular (weekly?) routine. As a result these plants never dry out, become waterlogged and rot.
Remember that your Yucca is a desert plant and hence adapted for drought. You probably need to water it infrequently. On the other hand other types of plants - Venus Flytraps, for example - are bog plants and need to be kept wet. A good start, in evolving a strategy for caring for any plant, is to find out about its native habitat.