LibreOffice 7.6 Help
Choose - Load/Save - General.
Mark Always create backup copy.
If the Always create backup copy option is selected, the old version of the file is saved to the backup directory whenever you save the current version of the file.
You can change the backup directory by choosing - LibreOffice - Paths, then change the Backups path in the dialog.
The backup copy has the same name as the document, but the extension is .BAK. If the backup folder already contains such a file, it will be overwritten without warning.
Choose - Load/Save - General.
Mark Save AutoRecovery information every and select the time interval.
This command saves the information necessary to restore the current document in case of a crash. Additionally, in case of a crash LibreOffice tries automatically to save AutoRecovery information for all open documents, if possible.