When adding or editing a question, you have the option to configure its scoring.
Total Score
To include the question in the overall score, check the "Include in Total Score" checkbox.
Bonus Question
To have the question used as a bonus question, select the "This is a BONUS Question" checkbox.
A Bonus question adds only to the earned points of the shop, it does not contribute to the possible points of the shop.
For an example: if assigned a point value of 2, the bonus question would add 2 points to the earned points, and not affect the possible points.