Hi, @NancyShop !
Katy here from Shopify. I hope all is well with you.
There are a couple of methods which you may use to help verify ownership of your domain with third party services such as Google Webmasters. These include - via TXT record (the current method you are using), via HTML meta tag, or via File upload.
Regarding the screenshot above, it appears that the service is not able to see that you have added the correct TXT record to your domain's DNS settings. Instead it is only showing one which had been provided from Outlook.
Usually you will be provided with a token or record from the third party service which requires verification of domain ownership. You can then add this to your custom domain's DNS records. There is some more information on this here. Could you let me know if you have added the TXT record to your domain's DNS settings, based on the info that has been provided by Google?
If this does not work for you, I would then suggest to try a different method - for example the HTML meta tag method. We have steps to help with this from within our help center guide here.
I hope this helps - though do let me know how it goes for you, and if you have any questions at all.