Trying to set up digital set top box to our old LG tv model no CF-21F80KX . Have red white and yellow on set top box and 2 white and 2 yellow on back of tv. Kerrie

Please provide a model number for this TV, I would have thought being an LED tv that you wouldn't be needing a set-top box as it would be digital already.

On the back of the tv and the cable box should be red, white and yellow rca jack, the white and yellow are sound

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/jason_77a19afa8d604dee

Your old video recorder should have the cable with the red, white and yellow connection. Plug them into the red, white and yellow boxes in the back of the TV. Usually there is a small white box painted around those three boxes and it says "Video 1" or "Video 2" on it, depending on how many video connections you have. If you turn on your TV you need to push "input" on your remote control and select the option "Video 1" or "Video 2", it needs to match with where you plugged it in the back of the TV.

The remote control that came with my Digital Labs tv/dvd combo worked for about 2 seconds and never really worked correctly. Now, I'm trying to find a universal remote that will be compatible. Please help.

Make sure your VCR is on channel 3 or try channel 4. Also, make sure your VCR is set to VIDEO or VCR and not TV. 
A better way to do this is to connect the cable box to the VCR using the composite cable (yellow/red/white) cable. Then, connecting the cable box to your TV with component cable (red/greenblue) cables. This will only work if your TV has component in. If not, then connect the VCR out composite (yellow/red/white) to the TV. Or use the coax cable from the cable box labeled TV/VCR right to your TV. Make sure your VCR is set on LINE1 or LINE.

Either tune your TV to channel 2 or 3 or (on some TV's) to 91.
Then, connect the COAX-output from the set-top-box to the COAX-input on your TV, or connect the "output" Red/White/Yellow RCA-jacks on the set-top-box to the Red/White/Yellow "input" RCA-jacks on your TV.

Ive got 3 samsung tv's (lcd, plasma, DLP) and I use HDMI cables on all of them. Its the only way to get the full potential out of the tv. When you use the red/white/yellow RCA cables the signal is anolog aka "old technology". Component cables are good but HDMI is the best. HDMI is a digital signal and thats what all the components that go with the tv should be run on. If your dvd player does not have an HDMI output I would suggest getting one that has that output. As for the cable box most require you to upgrade to digital cable in order to get one with an HDMI output. If you dont want to spend the money on new components and run what you have now the picture will stay mediocre at best. Good luck hope this helped

Problem is probably with your cable box as you have confirmed that the set is working by using the dvd player, that is unless you have a bad cable for the cable box.

ok first connect the red/white/yellow output of the dvd to the top box red/white/yellow input. Get the extra a/v cable then connect to the red/white/yellow output of the top box to red/white/yellow of the tv a/v video input A/V1 or A/V2 and last connect the RF aerial to the top box antenna in.