How can we enter category details & Item details both the information in one page of bill

Hi there, @nazar-sinatrahol. I've got your back, and I'm here to ensure you're able to add a category detail and Item details when creating a bill in your QuickBooks Online (QBO) account.

You'll need to click the arrow beside the Category details and Item details to be able to select an item for both section. I'll input the steps below so you can proceed. To begin, here's how:

1. Access your QuickBooks Online company.
2. On the left navigational bar, click the +New button.
3. Under the Suppliers column, select Bill.
4. Click the dropdown arrow to select a supplier, and then fill in the necessary details in each fields.
5. Once done, click the Save and close button below.
   
   Feel free to refer on the screenshot below that I've attached.
   
   
   
   

For more information about creating a bill in QBO, feel free to refer to this article: Enter bills and record bill payments in QuickBooks Online.

In addition, I've got you these articles in case you'd want to import your bills to your QBO account: Import your bills in QuickBooks Online.

You may also check this article to learn more about entering billable expense in QBO: Enter billable expenses.

Should you need further assistance managing your bills in QBO? Or do you have any additional QuickBooks-related concerns? Know that you can always get back to me anytime. I'll be more than happy to help you. Take care, and have a nice day!