If I reset (format, reinstall) my Windows 10, or got a new laptop, but I have already had many movies scanned and arranged to my own preference on Plex, such as posters, collections, tags, etc.
What can I do to keep those data instead of redoing everything from start again?
Just like how we used to copy the “save” folder from a PC game and paste it back to the same folder after the game is reinstalled in the newly formatted Windows or purchased computer.
If you can, reserve a separate hard disk (or hard disk partition) for Plex’s own data.
That way it will survive even a full reformatting of the system drive/partition.
Here is a guide how Moving Metadata on Windows