Can I add a new categories to the items line? (I have change headlines, but can't add a new ones )

It's great to have you here in the Community, Itai.

I'm thrilled to help you with an easier way to categorize your products and services in QuickBooks Online.

Below are the steps to add a new category:

1. Go to the Sales menu and click Products & Services.
2. Select the More ▼ dropdown, then choose Manage categories.
3. Click on New category, then enter the name of the category.
4. Then hit Save.

To add an existing product or service to a category, follow these steps:

1. Go to the Sales menu and select Products & Services.
2. Find the product or service you want to categorize.
3. Click Edit from the Action column.
4. Select the Category ▼ dropdown, then choose one that fits this item. 
5. Then Save and Close.

You can also categorize multiple items at once. Simply check the box on the left side of all the items you want to categorize and choose a category from the Assign category drop-down list. 

For further reference, you can review the following article:  How to organize your products and services in QBO.

Additionally, I'm adding some articles that could help you manage and organize your products and services and provide helpful insights when you run reports in QuickBooks Online:

• Run reports in QuickBooks Online
• Customise invoices, estimates, and sales receipts in QuickBooks Online

If you have any other questions regarding item management within sales forms, or if you need assistance with other aspects such as reports or expenses, please feel free to reach out. I'm here to provide support whenever you need it.