Domain Redirection and Error 404

I have wordpress set up in its own folder under my root directory (www.domainname.com/wordpress).

When wordpress is set so that both the wordpress address and the site address are https://www.domainname.com/wordpress then the site appears, but to get to the site you have to type in https://www.domainname.com/wordpress. I want the site address to be https://www.domoanname.com, obviously.

I tried to change the site address in the settings section of the dashboard as per the instructions, including copying the index.php file and changing it to point at the wordpress directory. When I do this, I get 404 error site not found.

I then altered my domain name on the server so that it pointed at https://www.domainname.com/wordpress. When I do this, the site text appears at https://www.domainname.com, but I get an error 404 when trying to log in to wordpress admin. I’ve tried this with the wordpress site address set to /wordpress and also set to the root, but it makes no difference.

All I want to do is have the site show when you log in to the domain name, and to have the wordpress that runs it run from the https://www.domainname.com/wordpress directory. It sounds simple but I can’t get it to happen, please help.