# Why do linear momentum and angular momentum have to be conserved in ground frame only?

According the Newton's second law of translational and rotational motion respectively if the net external force /torque acting on a body is zero then the linear/angluar momentum is a constant . So when we do conserve them why do we always conserve them in the ground reference frame ? If we do conserve them in a nonintertial reference frame do we have to apply some kind of pseudo force ? ( if yes where and of what ?)