and also tell me which command is used to change the units of dimensions initially as well as during proceeding to sketch??
You dont usually print 2d sketches with proe because its a 3d modeller. You can save as pdf and use your printer settings to scale. A better way is to create a drawing from your part or 2d sketch and save that as pdf so that the scale is accurate.
Many times people have been asking on this forum how to change scale, many times other people have answered.