MultiMC

1. Open MultiMC

2. Right-click on the FO instance

3. Click on Minecraft Folder

4. Open another folder to move your data to, like Documents

5. Copy the following files from the folder you opened in step 3 to the folder you opened in step 4:

   • saves: Your local worlds

   • resourcepacks: Your resource packs, if any

   • shaders: Your shaders, if any

   • screenshots: Your screenshots, if any

   • server.dat: Your multiplayer servers, if any

   • options.txt: Your custom options and keybinds, if any

If you want to restore your data, move the files you copied in step 5 back. If you're asked to replace the default FO resourcepacks, do not!