Hello ago Cabrera! You can only manage various companies in QB 2018 desktop. As I mentioned in the previous post, if you use QuickBooks Online you will have to set up one account for each business. However, if you are an accountant you can sign up to use QuickBooks Online Accountant for free. With this version, you can manage multiple companies but again they will require that you pay the monthly subscription for each.
You can learn more about QBOA here:https://quickbooks.intuit.com/accountants/?s_cid=Intuit.com&s_ev1=Intuit.com_Footer_QBAccountants