Access: Settings -> Business Info
1. Navigate to Settings page and choose Business Info. 
2. Enter Store Name.
3. Click Save button on top right and Clear Cache.

Store Name is used to make your customers remember your webstore. A good service or good quality of product delivered will increase the chances of customers returning to your store by just remembering your Store Name. It can be relevant to your products or services provided and does not have to be your registered company name.

It will be appeared on your footer with copyrighted.

It will also reflect on Invoice Header.