The 'response value labels' are labels used in the report for each question. Some labels in the report, like the 'items' column in the frequency table and the title for each frequency table/statistics pair, are based on the question type. For numeric questions you can also specify the numeric intervals. See the figure below.

Click on a question in the list and you will be able to customize the 'response value labels'.

Rating question:

Multiple question:

Numeric question:

Dropdown question:

Matrix question:

Question with in-text fields: