The "Visitor" Link - changes the color of the G2G tab text when you click on it ...and changes the color of the text in the main drop down lists at the top of the page "My Wikitree", "Add", "Find" and "Help" when you click on one/or all of the links.
You can see which ones you use and the one's you never click on as they remain white.
I have not tried signing out of wikitree to see if the color resets. Does it?? Otherwise its not really tracking a "visited link".
Signed out, then logged back in - the color of the links has NOT reset. So the sole purpose is to be able to choose what color you want that text to be, and if you want ALL of the text to be the same color you have to click on each and every one that it has an affect on to get that.
Reset within the options does not work, Once you set the color the only way to change it to another color is to turn off the whole Style section and refresh your page, it goes back to the "default" of white text, then go back to the app and in the "visited links" select your new color.