Not sure if this link below will be bookmarked to the place on the page but if it does not, do a search of "How do I move my Calibre data from one computer to another?". I move my Calibre data files from my laptop to desktop PC regularly as backup using a USB drive to transfer the files and the process is easy to import/export the files. Note, ensure you follow the instructions and create a new folder ahead of the import/export process to store your files. I just name my folder "New Folder" and have that folder saved in a place that you can find easily. Do not save it in a location on your desktop PC where it will be overwritten! I have the folder in my Books folder on my PC. Also, if you want to save older data files, just ensure you name the folder something other than "New Folder" and keep the "New Folder" only for current copies of the Calibre database. I rename my old folders in this format "New folder_Calibre_2023-11-27" but use what works best for your organization system.
https://manual.calibre-ebook.com/faq...ter-to-another