Clear decals

Any idea? 

I am not really understanding your question.  What exactly do you mean by them not looking good?  Are you saying the decals themselves have a different sheen than the paint?  Are you applying a clear coat after the decals are applied?

If I get you, the decal has silvered, or looks to be a different finish?

Yes you'll need to flat coat at the end. I have had that experience where you basically gloss coat the entire model to be able to apply just a few decals, and then have to go and flat coat the whole model. Sometines that's just the way it goes.

Satin paint or satin finish? I agree that it sounds like silvering, so I'm confused as to what finish you want as a final coat. If satin paint, then gloss for decals and a flat for silvering, then satin final coat? Or am I totally off base?