Your list belongs to this browser
Use Save title while viewing a film or series. My List keeps the selection locally, and choosing the control again removes it. A different browser profile starts with its own storage, so a list does not automatically follow you to another device.
Copy before you move
Open My List, choose Create backup and copy the complete text. It contains title selections and supported series checkpoints, not movies or viewing-account credentials. Keep the complete copy somewhere you can retrieve it.
Merge, then read the result
Paste the backup into Restore backup on the destination browser and choose Merge backup. Existing titles remain. Existing checkpoints are preserved when a conflict appears. The result message identifies what was added or skipped, so check it before discarding your copy.
Private windows are temporary
Private browsing and clearing website storage can remove the list. There is no need to create a list to browse MkvMovies, but if you use one, a backup prevents a browser change from erasing your movie-night plans.