You can configure one or more Microsoft Dynamics AX clients to open in a specific company by using the Microsoft Dynamics AX 2012 Configuration utility.
- Open the configuration utility.
- Verify that the configuration target and configuration that you want to modify are currently open.
- On the General tab, in the Company box, enter the three-letter or four-letter company identifier, and then click OK.
If you want you can export thiis configuration to an axc file you can click “Save configuration as file”. This allows you to open ax directly from the file
AX / Dynamics 365 For Finance and Operations blog 