Maybe you are connecting the Wii remotes the wrong way. There are two different ways to connect wii remotes: one time mode, and standard mode. One time mode can temporarily sync the Wii Remote to a Wii/ Wii U console, and is done with the 1/2 buttons and navingating through the system menu.
Standard mode will save connections, and is done by pressing the red sync button on your system, and then on the Wii remotes.