When building or editing a data set you can use the search option in the top right of the page to locate specific fields.
To use the search box, just start typing the label of the question for which you are searching. As you type, the tab titles (Contact, Request, Application, etc.) will be updated with the number of times the text you have entered appears in each tab.
If you expand the tab, you will only see questions that contain the text you entered. If they have already been selected, they will have a check in the box next to their name.