In some cases you may have a follow up question that you don't want to appear to all customers, only to those whom you will need follow up information from. In that case you may want to set the question logic to conditionally display a child question based on the response to a parent question.
Navigate to the Question and in related records select either Question Logic as Child or Question Logic as Parent
Either place is fine to start from as the form is identical and asks for the same information.
Make sure that the Parent question is mapped to a field.
You will want at least from mapping if the information is already in your system. If the information is generated as part of this form you will will want From and To mappings. Click here for instructions on mapping to a field.
Click + Add New Question Logic
How the page appears on the portal before you answer
Note that the question in the logic screenshot above is not visible. If you click No you will be able to continue to the next page.