Precomps (child comps) have a live relationship with their main comps (parent comps). Hence, any updates you make to the child comp will be reflected in the parent comp.
The description of your issue isn't clear but I'll take a guess that you are experiencing pixelation in the parent comp. Depending on what you're doing and to the type of layer you're working with the solution will vary. Let us know exactly what you're doing and to which type of layer (video, vector, raster graphic) you're applying it to.
BTW, for newbie Qs, please use the COW's AE Basics Forum
here.
HTH
RoRK
Intensive AE & Mocha Training in Singapore and Malaysia
Adobe ACE/ACI (version 7) & Imagineer Systems Inc Approved Mocha Trainer
