How the contact form label bootstrap tooltip popup onhover message position can be modified?

Question

I am building a website, and I would like to modify the CSS position for this floating box message that is displayed when the mouse pointer is hovered over a form field label.

How can it be achieved? What is the file that I have to edit (override)?

https://docs.joomla.org/How_to_add_tooltips_to_your_Joomla!_website