I purchased a nice full 12″ Schefflera about 2 weeks ago. It had white water deposits on the upper leaves only. I used tap water and cleaned off each leaf and sprayed it with leaf shine. I left it in the plastic 6″ pot, but planned to repot it after I bought a new pot. I noticed it was starting to drop off what seemed to be nice green healthy looking stems (from the main stalk). I changed it from the location from my kitchen nook to the kitchen counter. Both have good indirect lighting, but the kitchen counter has more. I don’t know what to do.
Try putting it in a spot where it will get more light, probably near a window, without direct sun; it sounds like acclimatization stress. Don't worry about repotting until the plant has stabilized. Growers put their plants in good potting medium and fertilize them well, because they're interested in strong, fast growth. You can leave it in its grow pot for a year, unless the soil gets so full of roots and the plant grows so much that t's toppling over.