Why is it i spent 3/4 of an hour making sure my wing skin fits perfect and i go to ca it on it moves on me 1/16 of an inch [:@][:@][:@][:@] i know have to either try and fill the 1/8th gap with a sliver of balsa of fil it some how...

We've all been there at one point or another. Fill with some scrap balsa if you can then smooth over with some balsa putty.
Use pins or something similar next time to hold the skin in place until you apply the CA. Pin holes are easier to fill then the gap you now have. And a lot less fustrating.
[&:]

would the tpins work on a 81 wing span and i filled the gap with some med ca and a bit of filler

I'm using poly glue and ziplock bags full of lead shot to do my wing sheathing. Nice results so far.