Change surface settings for multiple objects

Hello,

I have a large model that I have exported from Daz 3D. The import to Blender 2.90 went well. However, The majority of the materials/textures displayed look like they have dark spots all over them. Through playing around and comparing affected objects vs. non-affected ones, I have figured out it is related to the “surface settings” - specifically ‘Normal’ which is set to ‘Default’ on the unaffected ones. I found if i change the normal setting to ‘UV’ or ‘Normal/Map’, it fixes it.

So it seems I can fix this but I have to individually select and change this setting for 100s of objects including each surface/material that is part of the object. (E.g.: I have to change, hands, feet, torso, shirt, socks etc. individually on each figure). Is there a way to select multiple surfaces and make 1 change?

Thank you in advance for any help.

PS: since the unaffected surfaces have their normal set as ‘Default’ what is the ‘default’? I can’t seem to find this as a selectable option.

I will try to post screenshots which should clarify my question, but not sure if I am allowed.