Bodhi of Ankou said:

Yea take it to the repair shop. If I understand what your saying the exact same thing was wrong with the first acoustic I bought, but far worse then whats wrong with yours, they adjusted the bridge and a couple frets to fix it

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danielx said:

Doubt that will work, and if it does, its because changing strings somehow changed your neck relief. Just because its a lighter string doesn't mean it will make it any sharper in pitch.

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I think the neck relief bit is a big part of it. But there is no question that string gauge impacts intonation.

Best bet is probably a repair shop. Having your instrument set up by a pro once a year or so is worth it... unless you are truly dedicated to learning how to set it yourself. I just like to play.

x Ju x said:

I'm not 100%, but I think it's fixed by adjust the truss rod that goes down throughout the neck.

It's adjusted by turning the bolt that's visible at the base of the headstock where it joins the neck, under the strings. Some are covered, but some are visible.

It's really sensitive when turned, and you only have to turn it a tiny amount, but I've never done it, so I'd recommend bringing it to a shop.

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