How can I combine questions from different Quizzes / Worksheets
You can copy questions from a Quiz/Worksheet/Split worksheet into another using both the web editor and the OSX/Windows tool.
Using the web editor
When you're editing your Quiz or Worksheet, press the cog icon at the top-right corner of the editor and select 'Import from widget'.
Now select the questions to import and press the 'Import' button to add the questions to your current widget or press the 'Clear & Import' button to remove all questions your widget currently has and import these selected ones.
Using the OSX/Windows tool
Make sure the widget you want to copy from is saved on your machine.
Then open the widget you want to copy the widgets into, either a Quiz or a Worksheet, and go into the 'Quiz' or 'Worksheet' menu and select 'Import questions from'. You'll see the list of questions in the quiz you opened. Select the ones you want and press the 'Copy' button.
Save or upload your widget.