Change tray icon info/overlay text

Hello, when you put the mouse cursor over a tray icon, some text is displayed, which is most often the name of that icon's app. What kind of app/editor would let you change it?

Since most icons are embedded in an application's .exe/executable file you'd have to rewrite that file to make changes to it. That probably would require permission from the publisher of the program or otherwise be illegal.

Let's say it's about a free app. There are some apps that let you change the exe icon. But that text.. I didn't find.