Leave settings the same. They were researched to be the best, most optimal settings. Changing them to fit different markets is curve fitting and counter-productive.
Compare what Buy1Sell2 says about indicator settings to the quoted passages of Gerald Appel that I captured in screen shots below. As DbPhoenix said, you're starting point should be with the system designer who created the indicator - not what some obviously uninformed & ananonymous internet forum nickname has to say. Buy1Sell2's advice is completely opposite of the MACD's original author.
Since you're using MACD I'll assume you have more than a passing interest in finding out more about it. Gerald Appel, the technician/analyst credited with MACD's creation, has a book called
Technical Analysis: Power Tools for Active Investors. Chapter 8, "Advanced Moving Average Convergence-Divergence (MACD): The Ultimate Market Timing Indicator" should be of especial interest to you. However, you would get the most out of that chapter by reading the chapters that come before.
For example, though Appel is writing about indicators, he does not advise using them in absence of price action concepts such as Support & Resistance:
In fact, some here might be surpised that much of Appel's understanding of technical analysis sounds remarkable similar to Richard Wyckoff's description of price action:
Appel also makes a point of noting that the "out of the box" defaults is just that - a "default." The MACD is a tool, and this tool can be adjusted to various conditions, markets, bar intervals, and time frames. He himself demonstrates that in this chapter where he explains how to use the indicator he himself created:
Finally, he cautions that while MACD may seem perfect to some, that it is not so simple as that. For example, you might be interested in studying, and perhaps applying to your own trading some of the suggestions that he provides beneath this section header:
Why would there be additions to the basic ruels. Well, for one thing, Appel tells us this:
Look above to the Appel materials and see that not only is he an advocate of indicator trading systems, but he is also a proponent using what some refer to as the straight line approach (SLA) or, more lovingly, "Scribbles" as context in which to deploy those indicator systems.
You can find my original post in context here:
When Indicators Don't Lag