Are you referring to the name that shows in the right side of the Gear icon as your business name? If so, you can change its name by editing your personal name info in your Intuit account. Let me guide you how:
Click the Gear icon and select Intuit Account.
Go to the Personal info tab and enter your business name in the Name field.
Sign out and sign in again to your QuickBooks Self-Employed account.
If there's anything else you need, you're always welcome here in the Community to post again. We'll be always around ready to help.