Hi there!
I would highly reccomned leaving that setting alone if possible. I guess it’s a matter of opinion, but I feel like there are many who would agree that it’s good practice to leave it to the user to decide whether they want to open a new tab or not.
With that said, the setting can be changed retroactively using the methods outlined here, or if the site is hosted by us, have the contact on file reach out to us to make the change for you.