Нужно поставить предложение в косвенную речь, в прошедшее, настоящие и будущее время: they thought that some kind of uniform would help to stop it
They think that some kind of uniform will help to stop it ( будущее) They thought that some kind of uniform helped/ had helped to stop it( прошедшее) They think that some kind of uniform help to stop it( настоящее)