The white coating is probably a combination of decal adhesive and reacted Future. If using Future as a gloss clear coat, it's best to let it cure for at least 24 to 36 hours per coat, preferably a lot longer, perhaps up to a week. The Micro Sol/Set can start to partially dissolve the Future otherwise, which is, after all, a water-based, acrylic, synthetic 'wax'.
To remove the white appearance, gently wipe over with a damp, soft cloth and let it dry. Apply a further coat of Future to the area (by brush is fine, ensuring any drips, sags or runs are wicked off using the edge of a piece of tissue.) Once it dries, it should be gloss and clear again - but let it cure as above before applying any decals.