A #6 can do a lot of work. Edge jointing is always a challenge. To set the depth of the blade, adjust going forward. This will keep the blade notch in the adjustment tight against the planning action so there isn't any back slack and the blade won't move. Then set the lateral adjustment for the blade. If this isn't straight across the plane sole, you will cut a bevel, since the blade will be cutting deeper on one side. It's normal that you will need to adjust the depth a little more after making the lateral adjustment. With handplanes, try to do just enough and no more. Over doing will just cause problems with little inaccuracies getting compounded. Stop after two passes and check your progress. just cut the areas that need it, not the whole piece until everything is ready for that one last unifying cut. It can take hundreds of hours to master handplanes, be patient, think it through.