My tree is turning yellow. I water and mist it every week what can I do?
You didn't mention the available light and that is the most important factor. It should be close to and in front of a moderately sunny window. Without adequate light, nothing else you do will matter much.
Misting does nothing as it increases the humidity for all of about 15 minutes after you do it. Besides, NIP's have shown that they can do well in very dry air as long as they are watered properly.
Water yours thoroughly - until some water trickles through the drain holes - when the top inch of soil feels dry.