New TV's have bunches of hookups so you have to be sure you are using the right cable and putting it in the right input.
The Yellow is usually the old style (standard) video connection then the red/white are the audio (simple stereo)
There is also a component video cable connection that is made up of 3 wires for the video and two for the audio. in the picture below the first two are audio and the rest are video on the nice new TV if HDMI is not available this is the way to go for a better picture.

Now what might be confusing is you may be putting the old style yellow video into a port that should be used for a component connection. Look at the back carefully it is very likely that Video 1 is a component connection (you could have 2 sets of these)
Take a look at this picture

See on the right the Yellow/White/Red that is the old style hookup video/audio right and left
the connections in the center are component connections 3 for video and next to that 2 for audio hope that helps.