The nine members of the Bangor City Council unanimously chose Councilor Sarah Nichols to serve as the group’s next chairperson during a meeting Wednesday night, marking a dramatic shift from earlier in the day when the group failed to agree who should hold the position. After the appointment, the audience of about 50 people gave a standing ovation to Nichols, a 28-year-old who was elected last week to a second term on the council.