The last thing was a manual for a Canon printer (should be a PDF and I have Adobe). This problem just started recently. It is everything and, no, I'm not using a third party download manager - just downloading direct to my computer from Canon site and same with some others.
Next time you download a file, use the Save As option and direct it to a New Folder somewhere else on your drive or partition, preferably and external resource USB Thumb Drive or external USB Drive.
See if that makes any difference.
Also....
Can you successfully edit the file extension and convert the PDF file back to a .pdf instead of a .tiff?
It might be worth the effort to install one, just to test to see if your "Save As" options in one or both of those are restricted too.
When you create a local file, a new text document for instance using notepad or wordpad or another file format using another installed program.
Are your "Save as" restrictions also present.
Say in "Paint".... can you create a new file and save it as a .bmp or .jpg?
Now I'm confused. Your OP said "Every file (including applications) download a tiff files. Some are applications, some are pdfs, etc. How can I fix this in Windows 10?
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