Make sure the succulent is not in direct sunlight. If you keep the succulent indoors, make sure it gets enough light. The sap of the plant can cause skin irritation. Your succulent can turn yellow from overwatering or underwatering. The main cause of your succulent turning yellow is excessive water. Avoid storing it in the afternoon as the scorching sun can cause the roots to lose as much water as possible. After repotting your Sempervivum do not water it. It should dry completely before you repot.