Hi @smlbz - Try these steps:

1. 1) To get the app to launch without opening any company file hold down the option key while launching the app. This prevents QuickBooks form opening your previously used company file.
2. 2) Then select your company file from the "No Company Open" Window.  Hold down the command key while opening the file. This prevents the last used windows from opening.
3. 3) Then go into QuickBooks->Preferences. Select the Toolbar & Tabs icon in the 3rd row down and then uncheck the Use Tabbed Windows checkbox.
4. 4) Avoid opening the home page.