SSL lock not showing and securing digital downloads

Hello, I have SSL on my site. My SSL is installed and working and I’ve changed general settings in wordpress to https: but when you get to the secure pages the HTTPS and the lock only show up for about (1) second and then disappear. How do I set it so so the https:/ and lock are visable to the customer when they are on the site?

Also I sell digital downloads pdfs that are set to force download. If I am using forced download and the the customer receives the pdf from a link in the email after the order is processed, do I still need to set up an absolute path for them to hide someone sharing the links to the pdfs that are for sale.

If someone could help me out on this, that would be fantastic?

Thank you,
Moritz