When you create a new questionnaire, or modify an existing one, you have to open a test-editing tool, which you can use the following way. 

The editing field of the test making tool

Find existing tests

You can find the tests that you created or were shared with you in the Test Storage, by clicking on 'Questions' in the main menu, and select Test storage. 

Here you can see your Personal test storage, where the tests that you can edit are stored. 

You can edit tests by clicking on their name. This way the editor field will appear. You can import questions from your Question banks, or the Question banks of scenes. 

Select the questions that you would like to add to the test, and drag them to the editing field on the right.

You can add Random blocks and a Page break. By adding a page break, the questions in different page blocks will be displayed on different pages, so students will not see all the questions on one page. 

You can delete questions by clicking on the 'X' on the left side of the row. 

The order of the questions can be modified after dragging them to the field on the right, by dragging them to the desired position. 

You can add entire folders to the test, by dragging them to the editing field. The folder will be added to the list as one item, but you can view the questions it contains by clicking on 'show' on the right. 

If ready, you can save the test, or click on 'Save as...' if you would like to save it under a new name.