Secondary profession change?

I was just wondering if later on in the game if you are able to change your secondary profession out for another. And if so, how, when, and how many times can you.

thanks

Yes, after you ascend or become weh no shu or beat the mission hunted in NF, and as often as you want for 500g.

You can change it how many times you want. But you mut pay 500g for each profession, but after you've unlocked 1 profession you don't have to pay.

Rest you can find here: http://guildwars.wikia.com/wiki/Secondary_profession

If so: Yes
How: Prophecies - Beat the Doppleganger in the Crystal Desert and then beat the quest from Vanya and the small quests to unlock each profession.
Factions - Beat Naphui Quarter and then talk to the profession changer (I forget his name) and pay 500g to unlock a each profession if you like.
Nightfall - Complete the Building the Base quests, then talk to the profession changer in the Command Center and pay 500g to unlock a profession if you like.

How Many Times: Once you have unlocked a secondary profession, you can change between that and your prior profession as often as you like, as long as the profession has been unlocked (through quests in prophecies or paid 500g in Factions or Nightfall). BTW you wont lose prior learned skills from your original profession when you change secondaries.

There's a profession changer in the Battle Isles too, people forget about that location sometimes too.

It is free for Tyrians if you do the quests in the desert agian.