In Beanworks, you can view other user's invoices, but you cannot make any changes to invoices until you are the owner of the invoice.
Here are the steps on how to code another user’s invoice in BeanworksAP (provided the invoice is in an editable status: IP, N, RE, or R):
Once you're in the details view, you can take ownership by clicking in the 'Owner' field to activate the user list. Start typing in your name and when you find your name, select it by clicking on it to change the owner to yourself.

Now that you are the owner of the invoice you can begin coding the invoice.