yes, hawaiian umbrella tree would be schefflera arboricola. Looks something like this, right?
https://www.gifttree.com/images/super/70 ... Bonsai.jpg
Gnome is right--it will do much better if outdoors as much of the year as it can be. When night time lows get down to 45 degrees F, then bring it in for the winter. If indoors, it needs a good south facing window. If you bring it out now, you need to bring it out to a shady spot and then gradually increase the sun exposure.
You never want your schefflera to dry out completely, but you do want it to dry some between waterings. Always water it thoroughly so that water is running out the drain holes. Then don't water it again until the top part of the soil has dried a bit.
Have you been fertilizing it?