How to add customised fields in import invoices?

Welcome to QuickBooks Community, @vaishali_bhandaw. I can help you import your customized templates. 

First, I want to make sure if the Import Style feature hasn't turned on yet in the Settings preventing you from seeing this option. Let's enable this feature by performing the steps I outlined below: 

1. Go to the Settings icon at the upper right.
2. Select QuickBooks Labs.
3. Scroll down to Import Style plug-in, and toggle the switch to ON.
4. Click Done.
5. From the Gear icon, click Custom form styles.
6. At the upper-right, click the New style drop-down to see and select Import style.
   

Here's a detailed article to help you import custom form styles in QuickBooks Online. 

Additionally, you can visit these resources to learn other ways on how to customize your sales forms in QuickBooks:

• Add, customize, or remove logos on sales forms.
• Customize invoices, estimates, and sales receipts in QuickBooks Online.

I wish you and your business continued success. Please let me know if you have any other questions. Take care and have a great day!