Go to Connect, select a study you would like to modify (only studies with a special icon can be modified). Then got to the Query tab and in the section Questions got to the three dot menu. On the list you will have 'Edit questions and sections' and you will need to select the study you want to edit.
Select a question
Select a question you want to update with a new entry (an empty placeholder) and look to the third column (the dictionary).
Click in this new line to any field for which you would like to specify a value (e.g., Code, Label, Stat value). The edition will be available and you will be able to write a proper value.
To specify the “no answer” and the “missing”, click the context menu on the right side of the row (next to the pen icon) and click “Mark as no answer” or “Mark as missing”.
Until you have specified values for the required fields, the questions will be marked as invalid and a red error sign will appear next to the question itself and next to the row with incomplete entry in the dictionary. These required fields are listed in tool tip over the error sign.