URL confusion and issues with site URL and WordPress URL

I have read quite a few articles regarding the wordpress URL and the site URL, and I am a bit confused and still don’t understand how to use them.

My situation:
– I have a domain name on whois.com (eg. https://www.myrealurl.com) redirected to a folder on a hosted server (eg. https://example.com/subdirectory)
– Both the WordPress and Site URLs are set to the folder https://example.com/subdirectory
– I have access to all the files and the DB on the server

The WordPress thinks that he is this long url with the subdirectory instead of thinking that he is https://www.myrealurl.com

There are lot of features that does not work now, like the users cannot modify their profiles, statistics are saying that the referral is https://www.myrealurl.com instead of the real referral, the location of the files are appearing as this long url for the customers displaying the wrong url with the subdirectory, and there are many other issues.

I’d like to resolve these issues, so the wordpress would think that he is https://www.myrealurl.com, and the path for the files should be like https://www.myrealurl.com/subdirectory/…

Could you describe me the way to do this? Can this be solved in wordpress, or in the htaccess file?

Thanks a lot,
Adrian