I have bought a new laptop PC for the family and transferred Minecraft (Java edition, versions 1.13 and 1.14) save files over from other machines, one of which which I used to run as a server for my daughters for us to play together, and where I played using my own Mojang account.
Transferring world data is just a matter of finding the mincraft app data (e.g. %appdata%\.minecraft\saves on a Windows machine), and copying it to matching location on the new machine. I used a USB memory stick for this, and it was very straightforward. The worlds look correct, no missing chunks or other glitches.
The worlds transferred over from places that used my daughters' Mojang accounts work as expected. On these worlds, they use the same accounts now as before, and when they start the games they have all the equipment, experience etc that they had before.
The problem is that when a world has essentially transferred "owner" - the single player or server owner used to be me, but they are logged in as their own account - they start the game with my character's equipment.
Oddly, if I join the game remotely as myself, I also get my old character's equipment, effectively duplicating it, but losing the new owner's stuff somehow.
I would like to set things on the new machine so the players get to continue the games exactly as they were, using their own accounts.
I have found the playerdata folder and looked at the files there, but not quite sure if manipulating them works. I tried a few things and managed to get it working using my Mojang account to host the server on the new machine with my daughter connecting from another machine and seeing the correct equipment etc. So I know the data is still there, but requiring this setup is not what we want - specifically I'd like her to be able to run the game in single player mode on the new machine, and be able to access her character's stuff.
Searches for how to do this on the internet just bring up transferring worlds in the saves folder again. That part is working already though, and I cannot find any advice about switching single player data files around with remote player ones.
I have tried switching the files in playerdata around in all combinations I could think of - using the date/time stamp to guide which file is being loaded in single player. But all of them result in loading the original single player data, not the was-remote-but-now-local player data that we want. I guess there is some other file or setting that needs changing, but I don't know how to find out what it is or how to change it.
