Can we add custom field under my customer form. I have tried but option is not available to add custom field. it show me sales menu only. Please help me.

Let me share some steps on setting up custom fields, Jansen.

Adding custom fields gives you the flexibility to include specific data for more detailed report insights. Here’s how to do it:

1. Go to the Gear icon and select Custom fields under Lists.  
2. Click Add Field.
3. Enter a Name in the name field.
4. Select All sales form. If you want this to appear on printed forms, enable the "Print on Form" option, or it will only appear on QBO.
5. Hit Save.

For more details on personalized fields, refer to the article:  Add custom fields to sales forms and purchase orders in QuickBooks Online.

Additionally, I'm sharing this article if you want to know how to modify your templates: Customize invoices, estimates, and sales receipts in QuickBooks Online.

I'm here for any questions about your sales forms. The Community is available 24/7 to help. Have a great day.