Segments, like questions, can be searched by keywords with or without Boolean operators and sorted by Name, Newest first, Oldest first, and Relevance. If you search for two terms, such as car brand, the system assumes you want an OR search. If you want both terms included in the results, you must add either the word AND (car AND brand) or the AND symbol, the plus sign (car + brand).
Only the segment names are indexed, so you will not see any search results based on responses. If I search for paid, I won't find this segment, even though one of the possible responses has the word paid in it.