If you need to upload files to a record and have those documents or images remain private, then you will learn how to do so from the steps below:
1. Add File Privacy Option
- Go to Setup > Object Manager > Content Version > Page Layouts > Content Version Layout
- From the Fields section, select File Privacy on Records to drag and drop the item to the fields section under Content Detail Version
- Click Save
2. Update Privacy on Records
Open the actions menu of the file you want to update and select Edit File Details. Adjust the File Privacy on Records to Private on Records.