In 2e their is a new mechanic called Social Maneuvering, in theory their are also regular social rolls and Extended social rolls. How do I decide which of these my players should be using in a given circumstance?
That's going to chalk up as situation dependent/Storyteller discretion. The toolkit design of the nWod game-lines offers you various options, but doesn't always provide the best advice on how to apply them.
I would do Social Maneuvering for more long-term conflicts where wearing someone down over time would be appropriate. Think plying the Prince for a favor. In this situation, opening the Prince's Doors may take place over several Scenes or several Nights. Whereas something simple like fast-talking your way past a bouncer should probably be handled with a single Social roll.
An Extended action still takes place within the same Scene, and is easier to track in terms of book-keeping than a Social Maneuver. A rule of thumb here might be: if it can be resolved in the same Scene, do an Extended roll. If it takes place over the course of more than one Scene, do a Social Maneuver. There is a severe risk of game lag if Social Maneuvers are over-used. The rules also explicitly call for Extended rolls in certain situations, e.g. interacting with Touchstones. Defer to those in those cases.
I'd like to also point out that you have other options. If you have the Danse Macabre supplement for 1st edition, and you feel like doing some house-ruling, you can adapt the Social Combat in that ruleset for your 2e game. You might consider doing this if you wish Social interaction to take on a more competitive feel on par with Physical Combat.
Oh, and don't forget, you could simply roleplay it.