Import/Export chats takes a copy of your conversations, and puts one back. The export is harmless; the restore has a setting that can erase your account's entire history, so it's worth reading before you use it.
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Taking a backup
Export Now packages up the whole account's conversations — not just yours — with their messages, reactions, notes, tags and the contact each one is with. The file arrives as an encrypted .zip, and encrypted is meant literally: it isn't a spreadsheet you can open and read, it's only useful for feeding back into this page. The one thing it doesn't carry is your media. Photos and documents are stored as links, not files, so a restored conversation brings back what was said and a pointer to the attachment — but if that file has since been cleared away, the link has nothing left to open. Two ways it reaches you: the browser downloads it when the export finishes, and a copy goes to your own email address. Save the download when it appears — the button only works while the page is open, and reloading loses it.
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The two ways to restore
Select File takes a .zip you exported earlier, and picking one opens the choice that matters. Merge Conversations is the additive one: it brings the backup's conversations in alongside what you already have, and any message already in your inbox is left where it is rather than duplicated. Replace All Conversations is not additive and not limited to what's in the file — it deletes every conversation and message on the account first, then imports the backup on the empty slate. Anything that happened after that backup was taken is gone, permanently, for everyone on the account rather than just for you. There is no second confirmation and no undo: clicking the red button is the restore. If you're recovering something you deleted by mistake, Merge is almost always the one you want. Replace is for deliberately rewinding an entire account to a known point.
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What a merge does to what's already there
Worth knowing before you merge an old file, because it's gentler with messages than with everything else. Individual messages are safe — one already in your inbox is recognised and skipped, which is what keeps a merge from doubling up your history. A conversation's own details are a different matter: its status, who it's assigned to, which team it sits with and whether it's flagged all come from the backup, so merging a file from last month can quietly put a chat back to the status and assignee it had last month. Notes and tags come from the backup too. So merge to recover things that are missing, rather than as a routine top-up over a busy inbox — and if a backup is old, expect the conversations it touches to be restored to how they looked then, not merely topped up. Contacts are left alone either way.