How to prevent people from opening my pdf on a website???

Hello, my name is Melissa.

I am trying to sell an ebook and I've had some problems.

Before launching it for sale, I decided to prove how efficient my security restrictions were, and to my misfortune, they proved to be useless.

It was as simple as entering on a random website (like SmallPDF, for example) and unlock the password, just like that. I cannot allow that to happen, since my potential clients could afford to copy and use my material.

I would like to know if there is a way to prevent them from opening my pdf file on the web. For example, if they try, when the page says "Upload File", that they can't upload it...or the website throws an error, or something like that.

Please HELP !!!