Button states/yet visited

First of all, I apologize for my english: what I’m looking for is a way to make a button as “visited” while I am visiting it’s linked content.

in a precise moment I want to know exactly what I am reading to, and a recognizeable color/state or somewhat of the button should be the way to.

may someone explain me how-to (a bit in detail! ;))

thank U so much in advance, Teo