Three combo uses ema 5 and 10, rsi 21 and adx 14 to give you buy or sell signals.
When the three indicators give the same signal then the histogram will turn green for buy, or red for sell.
Yellow means that the three indicators have not agreed on a position yet.
The values of the the rsi, adx and ema can be changed to whatever you feel comfortable with. The height of the histogram is tied to the main adx line.