Sounds like you need to take a trip to the dealer... You said this is the first bar and third chain. I'm assuming you bought the saw new, so this is the original bar for the saw. Also, did you buy your extra chains at the dealer? If you can give us a few more details I'm sure we'll get it figured out.
But, I'd advise you go to the dealer and have the chains ground in case they're worn or sharpend more on one side or the other. Then, have your bar checked out. It may need to be dressed - where they grind the top and bottom edges of the bar where the chain runs to 'flatten' this surface, and remove any burrs from normal wear. This will make sure the cutters are both flat as you try to cut, and keep one side from cutting more than the other side. As the service manager to go over with you what you should be doing when you're changing or sharpening chains.
And last thing I'd do at the dealer, is pick up a file kit for your chains. This will save you some coin the next time your chains get dull, and it usually only takes a minute to touch-up the chain. Once you get this down you'll find yourself chainging chains less, and this means less down-time changing and adjusting the bar/chain.
Hopefully this helps, but if there's anything else, feel free to ask. Welcome to the site.