Is this a datasheet view of a subform? Don't really know what you mean by 'label for a field'. Labels are separate controls that as far as I know, don't exhibit resizing behavior like you're describing. Nor do they have Can Grow or Can Shrink properties. I think you mean datasheet field header.
If so, in what view of the form are you resizing? It should be form view: you resize by dragging then save the form. If the db is an mde or accde I don't believe you can save any design changes.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.