The File Management options are activated via Tools → Program Options → File Handling tab.
This section contains the following options for saving documents.
Saving automatically when closing the documents
If this option is enabled, the data will be saved each time the file is closed.
Save autorecover information
The option allows automatic saving of the file with frequency (in minutes) to be indicated. The program saves the data in a document called autobackup + filename. If the program or computer crashes, you can recover the data by opening this file and saving it as from the File menu.
Create backup copy
When saving to disk with the same name, the pre-existing version of the file is renamed with the BAK extension.
Refer to the Save page for further information.
Extension of files considered secure
This option defines the file types (eg: "pfd", "jpg", ...) and the url schemes (eg: "http:", "x-devonthink-item:", ...) that allow to open with a double click in the DocLink column of the Transactions table. Therefore, it prevents you from opening unsafe files or schemes. Extensions must be inserted without the period '.' initial, while the schemes must be inserted with a double dot ':' at the end.
If certain settings have been changed, program will restore the default settings when clicking on this button.