Hi there, davide-builderdi.
Thanks for taking the time to reach out here in the Community. I'd be glad to show you how to add different companies in QuickBooks Online.
To add a new company, you'll:
1. Go to quickbooks.intuit.com/online.
2. Choose the version of QBO you'd like.
3. On the sign-up page, choose Sign in.
It's important to note, each new company is a separate subscription. This article offers additional details on creating new companies in QBO: https://quickbooks.intuit.com/community/Getting-Started/Create-a-new-QuickBooks-Online-company-or-co....
Instead of adding a new subscription, you may be interested in the Projects feature in QuickBooks Online. According to the overview, "Projects is similar to job costing because it helps you organize all the pieces that make up a project. It includes transactions, time, and running reports so you always know how your project is doing."
Here's how you can turn on Projects:
1. Click the Gear icon in the top right corner.
2. Select Account and Settings.
3. Choose the Advanced tab.
4. Click the small pencil icon on the right in the Projects section.
5. Place a check in the box beside Organize all job-related activity in one place.
6. Select Save.
This write-up includes all the info you need about using Projects: https://quickbooks.intuit.com/community/Inventory-and-projects/QuickBooks-Online-Projects/m-p/186112. (*This feature is only available in QBO Plus).
With this information you'll be able to add a new company or project in your account. You know where to find me if you have any other questions.