Change Default File Format. Workbooks are saved as Excel Workbooks xlsx by default. Select Apps from the list.
In the tree structure on the left side of the Options dialog box click the plus sign to the left of LoadSave. In the Select Folder dialog box choose the folder you want to set as the default folder when opening documents and click Select. In the Files Settings dialog box click the Document tab.
The Preferences dialog box opens.
Workbooks are saved as Excel Workbooks xlsx by default. You may want your pdf files or email or music to automatically open using an app other than the one provided by Microsoft. You can change the default program for PDF files to open it in a program thats more suitable and feature-rich such as Acrobat Reader DC or Acrobat DC. Is there a way to change the default to save as jpg.