In the preferences under the item "General", you can set your own file extension for the entries.
The entries in Myary can also be saved in the Textbundle-format. Textbundle files are not simple files in the traditional sense, but directories that are disguised as files, all necessary information and additional files, such as attachments are included within the Textbundle file. The Textbundle format works with all markup languages supported by Myary. In order to activate the Textbundle format, the selection button in the preferences must be changed from plain text to Textbundle. More information about the Textbundle format can be found on the official Textbundle project page.