Domain not connecting

I tried to change the primary domain but I somehow managed to disconnect everything. I have three domains, I want one to be primary and the other two to be redirected to that one.

For some reason they all keep redirecting to one of the subpages no matter what I try. It is currently set up as Squarespace defaults (see the attached screen grab).

Could someone please help me recover or set up the DNS setings in the main domain? Then, reset the redirection to the subpage.

Thank you!