First, the judge has to approve any change of counsel in your case. Most judges are reluctant to assign a new lawyer once one has been appointed. You may have the option to hire private counsel. Judges are more likely (though it's not guaranteed) to approve a change of counsel for private retained lawyers.
I would recommend you spend whatever time you have left trying to retain private counse and asking your current lawyer to explain his advice. Why is he recommending you sign over your rights? It's one thing to be upset with your lawyer, but first make sure you understand his reasoning.