I have the follwing stem
My handlebar is a bit too much right and I am not sure what screw(s) I have to loosen the one on top (in the headset) or the two left on the picture above or maybe all of them.
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If you are saying the handlebars are angled to the right of being straight. You will want to loosen the two screws that are going horizontal across the steering tube. then you can straighten the handlebar/stem combo and re-tighten.
Be careful there are sometime torque spec on the Stem to make sure you don't strip it.