While you're browsing the available playlist, there should be a button on the side that says "Search Prefferences". Basically you can either pick a matchmaking based on the best connection or find a match based on availability (puts you in matches faster but there's a tendency of getting into bad lobbies)
Edit: Here's a summarization of all of the options available:-
-Best = Finds match based on best connection quality (greatly adviced if you have fast internet speed)
-Normal = Finds match that has a balance of best connection and availability
-Any = Puts you in any match regardless of any variables (if you're having a bad time finding lobbies, use this)