Subdomains enable you to set up multiple websites using a single domain. Just as app.myecomshop.com is our custom domain, store builder users receive a free subdomain. For example, one of my store’s website’s subdomain is https://chloescollections.myecomshop.com/
A subdomain is a second website that has its own unique content, but the same root domain. So setting up YOUR OWN personal subdomains would require you have connected YOUR OWN custom domain first.
For example, if you already have a website at "popcorn.com", you could create a subdomain (i.e. recipes.popcorn.com) from your domain provider.
The setup for adding subdomains is similar to adding a custom domain. Please refer to the article before this one for a more in-depth understanding.
To add subdomains, you would follow the same structure as adding a custom domain, however:
1) Move DNS records of your domain to CloudFlare
2) Select CNAME record for the respective domain
3) Add your sub-domain name in the name field (for example, something like: store.mydomain.com)
4) Type app.myecomshop.com
5) Add record
6) Claim sub-domain via DNTP store builder settings