Your Samsung TV may display "60Hz" regardless of the display settings, because the Info screen describes the input refresh rate, rather than the actual display refresh rate. However, Samsung TVs offer an Auto Motion Plus feature, which transforms this signal to display on your screen at 120Hz. Configure this option through the Samsung menu, which is assessable via the remote control.
Turn on your Samsung TV.
Press "Menu" on the TV's remote control.
Press "Enter" to select "Picture," which is already highlighted by default.
Press the arrow buttons on the remote control to highlight "Picture Options" and press "Enter" to select it.
Highlight "Auto Motion Plus 120Hz" and press "Enter."
Highlight "Standard" and press "Enter" to enable Auto Motion Plus 120Hz.
Press "Exit" to exit the menu.