Remove the current curtain rod by unfastening the screws on each end with a cordless screwdriver or regular screwdriver and pulling the rod down. Discard the old shower curtain rod.
Grip the Zenith shower curtain rod with both hands. Twist the telescoping end until the rod is the desired length.
Position one end of the Zenith shower curtain rod in the location of the previous curtain rod, turning it slightly until the screw holes match up. Put one screw through the holes and fasten into place. Repeat until each screw is secured. Push the decorative screw cover until it is flush against the tile, covering the screws.
Repeat on the other side of the shower.