Can you tell me who your domain host is please? If the domain is not hosted on Shopify and is instead hosted by a third-party domain provider, then you will not be able to change the A Record directly within the Shopify admin. The domain host should provide you with a login to a domain management dashboard and from here you should be able to edit the domain’s DNS settings, including the A Record.
Please also feel free to share your domain with me here so I can look at what might be causing the issue.
I believe this is your Shopify website—is that correct? If so, this would indicate that the domain is pointing to your store correctly. It’s possible that you’re still seeing the domain direct to your Wordpress site due to your browser’s cache. Can you please try visiting the site via an Incognito or private window, and let me know what you see? If the domain is working correctly then the domain should take you to your Shopify site each time.
I can see from the screenshot that you have shared that the A record is correctly pointing towards Shopify’s IP address (23.227.38.65). You will also want to ensure that you have a correct CNAME set up so that it points towards Shopify; you can read more on this here.
I’m glad I could help and am pleased to hear that you’re seeing the issue resolved on your end. Sometimes when a domain points to a new site, the old one will still display due to your browser’s cache and it’s not a true reflection of where the domain is pointing to and where it is set up. It’s a temporary issue that usually resolves itself.
Thanks again for reaching out and please let me know if you’ve any further queries.