Hi @Diana Weaver,
Thank you for posting in this community.
Question 1: Why do some of my list not display the option to download the document?
There are a few possible reasons and solutions for this issue:
1.One reason could be that you have selected multiple files or folders, which disables the “Download a copy” button. You can only use this option for a single document at a time.
2.Another reason could be that the offline client availability setting is disabled at the library level. You need to enable this option by going to List Settings -> Advanced Settings -> under offline client availability section, select Yes -> click OK.
Question 2: How to set up the documents so they always download instead of allowing them to open to a browser?
I tested it on my end and if it's an Office file, when I click on the file, it prompts me to open it in a local app. When I copy the link to the file and access it directly, it downloads the file.
1.For Office files there doesn't seem to be a way to find a way to set up a direct download of the file instead of opening it in the browser. But you can set the file to open in the local app by default:
Go to List Settings -> Advanced Settings ->Default open behavior for browser-enabled documents->select "Open in the client application".
2.For PDF files, we can set the way the browser opens the PDF file, set it to download. You can refer to this thread to set it up: https://learn.microsoft.com/en-us/answers/questions/1281501/opening-pdf-files-from-the-app-not-browser-in-docu
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