Hello, I've noticed that customers who purchased my first uploaded product are able to download and use my second product for free. I would like to restructure my files so that each uploaded product must be paid for separately. Could you please advise me on how to do this? Thanks!

As you mentioned yourself, currently when giving a specific price to a file, it is considered a “Tier”. So if a user has spent $5 on your project, they have access to all files with an individual price of $5 or lower.

The only way I can think to get around that, would be to make a new project page. This would force users to pay any amount set on that project.