Saving a new file in Design Review uses the default file type. You can change the default file format in the dialog box.
Saving or renaming an existing DWF file retains the original file format when it was opened. You can change the file type each time you save from the drop-down list in the dialog box.
If you anticipate that your DWFx files will be viewed using the Microsoft XPS Viewer, be aware that the XPS file format only supports JPEG, PNG, and TIFF image files from Design Review. So when saving a DWF file as a DWFx file, any images not supported by the XPS format are converted automatically and stored in the resulting DWFx file as PNG images.
Design Review cannot save an open PDF file in the Adobe PDF file format. If you modify an open PDF file, you must save it as a DWF file to retain the modifications. When saving the PDF file as a DWF file, the PDF content is saved as raster images. You can specify the resolution of the raster images on the tab in the dialog box before saving. The original PDF file remains unchanged.
To save a new, rename an existing, or save an existing file as another file type

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The Save File dialog box opens.
To save changes to an existing DWF file
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Changes are saved, overwriting the original file.