HI How can we change the Company GST Number so that the same reflects on the Sales Invoices too?

Thanks for joining the Community space, vishwanath-mohan.

I'll ensure you'll be able to change your Company GST number in QuickBooks Online.

You'll have the option to change the GST number in the Tax center if you already set up your tax agency. I'll show you how.

1. Go to the Taxes menu.
2. In the Tax dropdown, select the tax agency.
3. Click the Edit GST dropdown, then choose the Edit settings.
4. Enter your Company GST number.
5. Once done, hit Save.

You can also read this article if you haven't added your company GST for a complete guide: Setting up QuickBooks for GST.

In addition, you can visit this resource to learn how to make a GST compliance invoice in QuickBooks Online: Customise invoice for GST.

Don't hesitate to reply if you need further assistance with taxes or invoices. I'll be here to help you.