Finley from Shopify Here! Thanks for posting your question.
I understand you'd like to change the .myshopify.com URL you see when logged into your Shopify admin.
This URL is created when you first set-up your Shopify account and cannot be changed.
Is there any reason in particular why you'd like to update this?
I ask this because once you buy a custom domain or connect an existing custom domain, your customers will not see your .myshopify.com URL, as long as you set your custom domain as your primary domain.
At this stage, your .myshopify.com URL would only be visible to you or any staff when logged into the Shopify admin.
Create a new account and transfer your information
In saying that, if it's important for you to have a different .myshopify.com URL, you can create a new account with your preferred store name.
You'll be able to transfer some of the information in your current store, following our guide on backups and duplications.
In that guide, you'll see that that the following information is available to be backed up via a CSV file:
How are things going with the rest of your website?
If you're looking for the next steps to grow your business further, you may be interested in our video courses on Shopify Compass!
This is a free resource for you to learn about anything from marketing to store design. I highly recommend taking advantage of this as you'll find many tips and strategies from experts in different fields.
As always, should any questions arise, be sure to reach out to us!