Hey, @JBolin! Welcome to the Community.
The myshopify.com url is permanent on your account, and so it cannot be changed. In order to have it be something different from the business name used when signing up, you would need to create a new account, or use a custom domain. In your case, when creating a new account, you would need to use the business name ‘shopjbolin’ instead of ‘shop jbolin’ to have the url 'shopjbolin.myshopify.com' applied to your account.
I recently responded to another Community post discussing selecting a business name when signing up. Check it out! I elaborate further on how to enter your business name when creating your account so that you get the desired myshopify.com url.
Let me know if you have any other questions. I’m here to help.