had a problem placing decals

Don't "Take" them off the backing paper, "Slide" them off. Place the decal, backing paper and all, on the model where it needs to be and then slide the decal off right onto the model.

Never heard about letting decal sit in Future. Why would yo do that?

With big decals or small I leave them sit on the backing, place the backing and decal where I want it and then slide the decal from the backing right onto the model. I try to get it close to the final position but I don't worry about not getting it placed exactly. If it's not where I want it I'll slide it around until it is. If it won't slide easily I just cover it with a little water from a clean brush and it will generally float where I want it. Soak up the water with the corner of a paper towel and it will sit right down. Smooth it down to get rid of any excess water and air bubbles and apply decal setting solution.

Future is perfect for gloss cover. Many pro modeller use it.
I usually not dip decals into warm water. After spraying future (let it cures first), I dip decals into windex or window glass cleaner or whatever the name in your local shop, stick it to model as Scott Musicity said. Press the windex excess with very clean tissue and...
No silvering and perfect after drying.

well i typed that wrong, i let them sit in water then dipped them in future. the smaller decals came out great, it was just the big ones that gave me trouble. thanks for the tip musicCity.