How can I use hyperlinks within a single PDF-file?

Hi All!
I teach math at college level, and create most of my material with LaTeX -> ... -> pdf. LaTeX has a package that allows me to insert links to other parts of the same document. For example, when my text refers to an earlier Example or a Theorem, I can make that reference clickable.

Those clickable links still work, but for the life of me I can no longer find the back button! Imagine I'm lecturing, and I get the vibe that students need to see what exactly Theorem 3.47 said. I can click that all right, but I obviously want to then continue from where I was.

I used to have a pdf reader (most likely from Adobe) that let me do exactly that. How is this done with the current version? I would gladly tell you the version number, but I cannot locate the "About" item from its menus.

Cheers,

Jyrki