Lengthen dForce hair settings

fazzio349

Hello! I recently purchased the dForce EXzela Long Hair for Genesis 8 Female(s) (https://www.daz3d.com/dforce-exzela-long-hair-for-genesis-8-females). I wanted to make the length of the hair just a little bit longer. I went searching and found a few suggestions to lengthen the hair using the PS Generated Scale setting under the Surfaces tab. Unfortunately, that setting didn't seem to be available so I unhid all properities and there was... greyed out. I tried a different dforce hairstyle and got the same thing. The slider does nothing when I move it. Is this setting only available to certain hairstyles or am I missing an extra step here? 

Thanks for your help!

AJ2112

Try parameter tab