Can’t shut down PDFs

I have a problem with WordPress and PDFs uploaded into the Media Library. I create a PDF, using any on-line program and just upload it into the Library.

I copy the URL of the PDF in the library then go to the WordPress page that I’m working on and create a link from a word on that page to that PDF, using the link I’ve just copied.

All works fine until I want to close down the PDF and, then, there’s no way of doing so. The PDF is fine and clear but there is no button or any thing on the screen to shutdown the PDF and return to the previous page.

To explain a bit more, the WordPress program is on a small computer terminal, in a gallery, which visitors use for information about the gallery.

The only control available to the visitor is via the mouse, which allows them to choose, from a list, what they want to go next. There is a keyboard, with limited functions, but that is there for use by the gallery attendents – not the visitor.

I’ve read all I can find on PDFs but can’t find my particular problem like mine.

When I create a PDF using Excel 2016 the PDF has a small cross in a circle which close the PDF – similar to that when using Media Galleries – that’s what I’d like.

I’d be grateful for any help, please.