Click on the button Open at the Configuration - Editor Display - Syntax Highlighting dialog to open your wordfile. Close the configuration dialog with Cancel.
If you use the default wordfile.txt in the UEStudio program directory, scroll down in the wordfile to the line starting with /L3"HTML". At the end of this line you see the file extensions already associated with HTML syntax highlighting. You can add here MODULE without period. But maybe the maximum number of file extension is already used and you have to replace an other extension like PHTML for example with MODULE.
If your .module files contain only PHP and not HTML code, you can assign the extension MODULE also to the line starting with /L8"PHP". Save the wordfile and the .module files should be immediately highlighted with HTML/PHP syntax highlighting.
Best regards from Austria