I used this post
https://github.com/MichMich/MagicMirror/pull/1345
to add font-awesome5 but I am not able to get all of them working. Anyway, now I understand all.
Thank you.

OK, I think I may have found the solution…

I’ll start by showing you my calendar categories:

This might be helpful to have handy…

Font Awesome Cheat Sheet

Now the code to put in your config.js file in the calendar code:

"calendars": [
  {
    "name": "Family Stuff",
    "symbol": "heart@fa",
    "url": "Calendar link here"
    "interval": 24*60*60*1000,
  },
  {
    "name": "US Holiday",
    "url": "Calendar link here",
    "symbol": "gift@fa",
    "interval": 24*60*60*1000,
    "maxEntries": 50, "maxDays":365,
  },
  {
  // "name": "Birthdays",
     "symbol": "birthday=cake",
     "url": "Calendar link here",
  },
  {
  // "name": "KC Chiefs",
     "symbol": "football-ball@fa",
     "url": "Calendar link here",
     "interval": 24*60*60*1000,
  },
  {
  // "name": "NFL Games",
     "symbol": "calendar",
     "url": "football-ball@fa",
     "interval": 24*60*60*1000,
  },
  {
     "name": "NFL Playoff Games",
     "symbol": "user-secret@fa",
     "url": "football-ball@fa",
     "interval": 24*60*60*1000,
  },
],

Let me know if this works for you.
I have yet to try it, but now that I found it, I think I will. :winking_face:

Apologies, been kinda busy last few days…

I am looking for the answer to your question.

I haven’t used the default calendar for quite a while now.

I really like the MMM-CalendarExt modules, although, I never really thought about it until now, it’s the same way… same icon for each event.

I shall do some researching to see if I can find a solution…

defaultSymbol: "calendar",

And icons are same, nothing changed. Does not matter if it is holiday or event 1 or event 2 - icons are same.

I still do not understand - how to define icon for the specyfic event?

search fontawesome in google. It shows all the available icons.

as far as changing the icon for your calendar, try this…

in your config.js file, you need to add this line in the config section of your calendar…

defaultSymbol: "calendar", // Fontawesome Symbol see http://fontawesome.io/cheatsheet/

the following defaults cand be changed in this section as well…

maximumEntries: 10, // Total Maximum Entries
		maximumNumberOfDays: 365,
		displaySymbol: true,
		defaultSymbol: "calendar", // Fontawesome Symbol see http://fontawesome.io/cheatsheet/
		displayRepeatingCountTitle: false,
		defaultRepeatingCountTitle: "",
		maxTitleLength: 25,
		wrapEvents: false, // wrap events to multiple lines breaking at maxTitleLength
		fetchInterval: 5 * 60 * 1000, // Update every 5 minutes.
		animationSpeed: 2000,
		fade: true,
		urgency: 7,
		timeFormat: "relative",
		dateFormat: "MMM Do",
		fullDayEventDateFormat: "MMM Do",
		getRelative: 6,
		fadePoint: 0.25, // Start on 1/4th of the list.
		hidePrivate: false,
		hideOngoing: false,
		colored: false,
		coloredSymbolOnly: false,
		tableClass: "small",
		calendars: [
			{
				symbol: "calendar",
				url: "http://www.calendarlabs.com/templates/ical/US-Holidays.ics",
			},
		],
		titleReplace: {
			"De verjaardag van ": "",
			"'s birthday": ""
		},
		broadcastEvents: true,
		excludedEvents: []
	},

Feel free to ask if there is anything you don’t quite understand… :winking_face:

@nobita you wrote "you can change in other icon such as "calendar-plus-o " but what is this? A set of icon or what?

I am sorry, but I have no idea how to make it working.

By the way - there is nothing like step by step tutorial - in README.md there is only a link to fontawsome page but there is nothing written how to use it.