How to get amount in words on invoice? and how to i change width on header on invoice

Welcome to the QuickBooks Community, @userrushabhbhansali5.

I know how important for you to have an option to get the amount in words on invoices, as of the moment, you can only input the amount in numbers in the Amount field. The recommended workaround is to enter the amount in words in the Memo field. Please see the screenshot below for visual reference.

Also, here's how to change the width on the header of your invoice:

1. Go to the Gear icon and select Custom Form Styles.
2. Click Edit on the invoice template.
3. Select Content.
4. Tick the Pencil icon at the upper-right hand corner in the template's body.
5. Choose EDIT LABELS AND WIDTHS.
6. Hit Done to save.

For more details, you may refer to this article: Email and customise sales form. 

You can also, import custom form styles for invoices or estimates in QBO, for the detailed steps, see this link: Import custom form style. 

Please keep me posted if you have further concerns about managing your invoice in QBO. I want to make sure everything is taken care of for you. Have a good one.