4DS chart, page-3680

12, 26, 9 is your standard macd settings I think you'll find.

the slower settings are less responsive to gyrations.
similar to 20 day sma versus 200 in terms of response to SP movements.
when the 2 move together that's a stronger bullish TA signal.
when they diverge that's a more bearish TA signal.
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by converge what I mean is the 2 settings move together. Perhaps the wrong use of language here... Move in unison is a more accurate term.

this is basic and there's more to it.
@W3hunter is a good egg for this - they're his/her settings!
cheers.