Make the copy
Open My List and choose Create backup. Copy all the text in the output box, including the opening and closing braces. Keep it in a note or document you control before replacing a device, clearing storage or changing browsers.
Merge it in the other browser
Open My List there, paste the complete backup into Restore backup and choose Merge backup. Recognized titles are added once. Valid checkpoints are added when there is not already one for that series. An existing checkpoint is preserved rather than being replaced by an older copy.
Read the result
The message tells you how many titles and checkpoints were added and whether any unavailable entries were skipped. A title already in your list does not count as a new addition. Review the list after the merge so you know the choices you care about are present.
If the text is rejected
Check that the copy came from Zmov's backup box and was not cut short. Ordinary prose, an incomplete fragment or a backup from a different site will not import. The transfer contains saved-title references and episode numbers, not movie files, passwords or a streaming subscription.