What you need to do is this, in your model click on the feature you want to move, then click edit sketch plane. If your sketch is on the front plane then just click on the top plane. Repeat the edit sketch plane and then select your front plane. Your sketch will now be below the line if before it was above.
Do you have problems with chamfer dimensions in your drawing, especially if it involves more than one chamfer. then here is the answer to all your problems. If your dimension is pointing the wrong way for a multiple chamfer in your drawing then go back to your part model and select the chamfer, click edit definition, click in the property manager and select the first line, next click on the change direction. You can then go back to your drawing and see that the dimension has rotated, though be careful that the dimension is on the correct view.
