Create a copy before you need it
Open My List and press Create backup. Copy the complete text from the output box, including its opening and closing braces. Keep it in a private note you can reach from the other device. This records saved title identifiers and episode checkpoints, not passwords or video files.
Merge on the other device
Open the same Seez site in the destination browser, go to My List, paste the complete backup into Restore backup and press Merge backup. The status message reports what was added. Existing saved titles are kept. When the destination already has a checkpoint for a series, that checkpoint is retained instead of silently being replaced by an older one.
If the text is rejected
Make sure you copied the whole backup rather than only the list of numbers. Do not edit its punctuation. A backup from another brand is not a Seez backup. Entries that are not present in this catalog are skipped, and the result message tells you how many could not be used.
What is not included
Recently browsed pages and your viewing-country preference are not part of this list transfer. Neither are another service's watched history or subscriptions. After merging, open a saved series and check the episode note before discarding your original copy.