hi. you need to copy all the files from the chapter2 folder into the chapter1 folder. then start the game and see that the version in the starting manu is the chapter2 version. then do the same with chapter3- copy all the files from chapter3 folder into the comined folder that you have of chapters 1 and 2.
its a little hard to guide in the comments- if you join the discord server it will be easier and faster to help you there
