How to make open external links in the new tab by default?
 

How to make open external links in the new tab by default?

Is there an option in Atahualpa theme options can do it?

Thanks

sorry I don't understand the question. If you want to add a menu item to an external link, create a wordpress custom menu and add it there

I want to make opening both internal and external inks in a new tab, how can I do it?

There is nothing in the theme that will do this. You might find a plugin that will do it for you.