Not able to find the constraints option in the Rigidbody component

I am working on a game tutorial right now and I need to freeze constraints for a model prefab. I add a Rigidbody component and I want to freeze rotations on the x and z axes. However, I am not able to find the option in the component. Is there another way to access rotation constraints (I do not want to code the constraints at the moment)? Or is there something I am missing in the new version. Please do let me know. Thanks

Rigidbody component. It does not have the constraints option here at all!

I am using Unity 5.6.7f1 Personal