I need to show the username on the invoice how i can do it ??

Hello there, ameraaybak.

You can add a customized field and manually enter your username so it'll show up on your invoices. Let me guide you with detailed steps.

1. Go to the Gear icon, then select Accounts and Settings.
2. Select the Sales menu.
3. Click anywhere in the Sales form content section.
4. Under Custom fields, enter the heading you want for your username (ex. Username.).
5. Select Internal and Public check-boxes.
6. Click Save, then Done.

Once done, pull up an invoice to check the implementation of the update. I've attached screenshots below for your reference.

You can also display one by entering it in the Message on invoice field. If you're going to input it in the Message on statement section, it'll serve as the description for your invoice when sending statements to clients.

If you wish to personalize your form designs and add information about your business, you can check out the Customize your invoices, estimates, and sales receipts in QuickBooks Online article for the steps you need to take.

Please let me know if you have other concerns about customizing your invoices in QuickBooks. I'm just around to help.