Need logo to link to my welcome page, not my landing page

It's usually a case of adding something like this to Settings > Code Injection > Footer:

window.Squarespace.onInitialize(Y, function(){
  document.querySelector('.Header-branding').setAttribute('href', '/about-us-sonora');
});

Change '/about-us-sonora' to be the URL of the page you want visitors to reach when they click the logo.

Let me know how you get on. As you didn't include a working link to your site in the question I wasn't able to test it.