For managing projects within QBO, you might find this article helpful: Create and manage projects in QuickBooks Online.

Also, if you need to switch between companies in QuickBooks, you can go to Gear icon and then select Switch Company under the Profile column.

Furthermore, you can also refer to this article on how to add users and assign specific permissions: Add and manage users in QuickBooks Online.

Let me know if you need further assistance in creating a new company by leaving a comment below. I'm always glad to help in any way I can.