"Learn more"

How do you switch between ranged and melee attack in Heroes 3, for example, with Titans?

In SoD, you can't switch!
In unofficial expansions, such as In the Wake of Gods, you can switch by right-clicking on one of the buttons in the lower right corner of the screen (I don't remember which one, I think it's the button with the shield).

Added after 11 minutes

You really hit the nail on the head!
What's going on...

The topic is just named so well, "Learn More" ;) That's why everyone is jumping in to learn more :D