When a document is downloaded from the Document Library using the public link, it will be downloaded with the same filename that the document had when it was uploaded.
The filename is important because students who download the file will use the filename to quickly identify what the document is about.
In order to change the file name, you will need to upload the new version of your document with a revised filename. First, change the name of your file. Then follow the steps below to edit your document and upload the new version:
Click the Document Library icon from the CRM Homepage.
Find the Document that you wish to change the filename of.
Click the edit pencil for that Document
Click the Choose File button.
Select the Document you wish to upload.
Click the Save button.
Your document will then be uploaded with the new file name, using the same public link as before.