As far as I know, there is no setting that allows this view option to be explicitly specified.
However, MATLAB remembers your "last-used" preference, so in order to set the editor to always dock files in the tabbed format to which you refer, simply do the following:
1. Click the "dock" arrow in the upper hand corner of a single file. This will cause the file to be docked in the main MATLAB window.
2. Click the uppermost "undock" arrow in the editor tab (which is now in the main MATLAB window) to move the editor to its own window.
3. Open any other file. It will now be docked in the (now separate) editor window in the tabbed format you're wanting.
If you close the editor after doing this, your preference will be remembered the next time you open the editor.