Question about editing *.json files

So Im a big fan of “Romero” zombies (slow and tough - OK, fast and tough - not OK) and i would like to change “Classic” zombies to those matching with my “ideal”. The problem is what do i need to know about editing *.json files.
What i need to do with them, do Notepad++ will be sufficient etc.?
How to change few zombies from “CLASSIC” to “DEFAULT”? Or maby how to edit their movement values?

I dont want to make a nearly incapable zombie with ultra low movement (thats no fun at all), i just want to change their speed to slower.
I was playing Cataclysm when whales made it, i was playing with Cataclysm DDA with the early Classic zombies and it was super fun, but now… Im not fond of those.

I understand that this game meant to be hard or tough, but im a casual player - challenge is ok - but reasonable. Now when im playing with the default/classic zombies i can no more move close to city not even thinking to fight with them or to sneak past them - because there will be always a zombie on my way and then whole pack will swarm against me (meaning my characters are killed superfast).

So gimme a hand even if you think im noob because i dont know how to play this… I dont have whole day to play games and i would like to give atleast an hour for Cataclysm but not in this state, frustrating state…

You can edit the speed value of monsters in this file:

Higher speed means they get to move more often I believe.

Notepad++ is sufficient (in fact it’s what I use). Note that currently there is no attack/move speed split, meaning if you lower a monster’s speed it’s going to attack slower as well.

As for the play style, dynamic and static modes have a vastly different play style, and trying to use one on the other will only lead to an extremely quick death. In dynamic mode at the start of the game the basic idea is to Yolo-charge as fast as you can to nearby shops, grab what you can, then get out. Static requires a completely different approach. What you instead want to do is to approach the city from the side farthest away from the shops, and slowly take on the zombies building by building, luring them out and dispatching them before proceeding farther in. Imagine like the early game is like the endgame, with the idea that once you clear an area it’s not dangerous anymore, and you should do much better.