How to: Change an Item Within a Cell (Report Designer)
Only a non-container item, such as a text box or image, can be replaced by a new report item. If the cell contains a container item such as a rectangle, list, table, or matrix, the new item is added to the containing item instead of replacing it. To replace a container item, delete it. This causes the container item to be replaced with a text box, which you can then replace with another item.