Hi Yanie,
I'd forgotten that when you set the properties for the textile it doesn't in fact set the values for all the yarns. It has set the value for the textile - if you do textile.GetYoungsModulusX() it will return your changed value. If this is sufficient for your purposes then that's fine. If you need the values to be set for individual yarns then you will need to use Yarn.SetYoungsModulusX etc.
Louise
Material Properties Specification
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