Hi @Michelle Unser ,
- Only Office files force users save such properties (other files require online properties edition+CheckIn, what is a very boring work).
- When One download these files from sharepoint and share by e-mail, USB drives, etc, these files don't keep such properties.
- You could change the filename to keep these files such properties.
A similar post for your reference:
https://social.technet.microsoft.com/Forums/en-US/5c445010-152a-4fd0-a4f9-b71f2a2476e3/how-to-give-naming-convention-for-a-document-library?forum=sharepointgeneralprevious
Here is a nice article about naming convention
https://www.spguides.com/sharepoint-naming-conventions/
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