Why are the leaves laying flat instead of standing straight up?
Certified GKH Gardening Expert
It would help if we knew if this was an indoor Yucca Plant or outdoor plantings.
Overwatering could certainly be a cause of the plant leaves falling open.
Make sure the soil is drying between watering.
In the case of an outdoor Yucca, certain varieties, the parent plant will die off and the offspring shoots then grow. If the parent plant leaves are lying down, they can be removed, making room for the new plants.