When creating squash deformers, you can first set creation options and then create a deformer, or you can immediately create a deformer with the current creation options. If you’re not sure what the current creation options are, checking them before you create a deformer can save you some time adjusting the deformer’s attributes afterwards.
You should avoid changing the number of a deformable object’s points (for example, CVs, vertices, or lattice points) after you create a deformer. Changing the number of points can lead to unexpected deformation effects. Try to be sure you are happy with the deformable object’s topology before you begin using deformers. Save a copy of the object in case you want to do further modeling.
See Create Deformers > Nonlinear > Squash and Advanced deformer options.