To adjust the position of the stop bead on your beading thread, grasp the bead with two fingers and slide it up and down the beading thread. If you added a second pass of thread, this might be difficult to do, so make sure that you have it in the correct position when you make that second pass.
Once you are satisfied with the position of the stop bead, you can string on the first set of beads needed for your project.
To remove the stop bead, grasp it in two fingers and gently pull it off the beading thread If you have split your beading thread, you will not be able to remove it.
