Chat history is saved
automatically in the line cloud server, you can uninstall the app, you
will lose All your chat history. So Create a backup of chat history.
On the down arrow button on
the top right to save and to tap conversations you want to enter the
chat room Then select Settings Chat. Tap on a text file backup chat
history, or as a backup, select the backup. Your Dropbox backup, for example, will be stored in your cloud storage.
If you choose a text file as a backup Chat history can not be restored.
If you choose to backup all, you can import it to restore chat history.
