There are 2 types of switches.
1) Regular Switch
Regular Switches are a very useful tool. You can use them to mark progress of your game, to change where the player is transfered to, make events only occur once, and so on.
By default, all switches are turned to OFF. This means that the game is registering that you're not making any changes, and it will keep repeating events on the map the way you set them up, even if you use "Erase Event" (which only erases it until you exit the map and re-enter). So, in order to make events happen once, you need use the switch command. You could also make a lot of copies of the same map, but it's not very practical to do this. It's easier to just learn about switches.
First thing to do is to make a good name for each switch you use. For example, you could name a switch "End Intro" and use it at the end of the introduction. The more specific you are with the name, the easier it is to keep track of which switches you need to turn on and off.
There are only two other things you need to keep in mind. The first is that you have to make sure you set the switch to "ON" when you want to initiate a change. So, for example, at the end of your intro you would set the "End intro" switch to ON. That would make it so you don't see the intro again if you walk back to the map.
If you ever want to go back, you can just turn the switch to "OFF" at the end of the event, and it will go back before the change. For example, if you want to see the intro again, you would turn the "End intro" switch OFF. When you walk back to the map, you would see the intro again.
The second thing to remember is that you have to use conditions and conditional branches. The conditions tab is in the upper left area of your event editor (where it says "Switch" and so on). When you want something to change, you need to click the box next to the switch (or self switch). The game will check if that condition has been met and it will use this new page instead. If a switch is ON, the page that has that switch in the condition will take priority over the default page.
You can also use the switches in common events and the conditional branch. I won't complicate things by explaining these right now, so take a look at the tutorials forum if you want to know how they work - or let me know if you need help with it specifically.
2) Self-Switch
This is just like the regular switch, but it only works on that specific event. For example, if you want an NPC to say something different after you complete the quest, you would set "Self-Switch A" to ON. Then, you would make a new page and use the condition "Self-Switch A is ON" (click the little box next to that). Then, in the event editor box on the right, you would put a message with a new text.
Self-Switches are useful when you want to have something that's specific to just one event such as a treasure box, NPC text, make sure that a specific event doesn't keep happening when you exit/re-enter the map, and so on.
