Glad you made it here, user12557.

Just to confirm, are you trying to change your company email that you use for your sales forms? If so, changing or updating the company email you use for sending invoices in QuickBooks Online is pretty easy. Here are the steps:

1. Click the Settings icon at the top and pick Account and Settings. 
2. Select Company on the left panel then click the Pencil icon on the Contact Info section.
3. Enter your new email address in the Company email field and put a checkmark on Same as company email.
4. Click Save, then Done.
   

Moving forward, the system will apply the new email address for your invoicing.

For future reference, you can also check out these articles for further guidance:

• How to email or print an invoice
• Change the email address you use to sign in

If you're referring to something else, please add a comment below. I'll be sure to help.