We have been trying to set the channels in our old picture tube tv. it scans through the channels and once complete, you can only watch the last channel found and once you go to change channels, it remembers none. this occured after not being able to watch a video one day, so we attempted to rescan the channels and now can not watch anything.thank you

I can provide some general steps on how to scan for channels on a TV: Make sure that your TV is connected to an antenna or cable input. Turn on the TV and go to the main menu or settings. Look for an option to scan for channels or auto-tune. This option may be labeled as "Channel Setup" or "Channel Scan." Select the option to scan for channels and wait for the TV to complete the process. This may take several minutes. Once the scan is complete, you should see a list of available channels on your TV. If you're still having trouble, I suggest referring to the user manual that came with your TV for more specific instructions. Alternatively, you can try contacting the manufacturer's customer support for assistance.

A channel scan is a vital part of utilizing your cable TV service. When a coaxial cable is connected to a TV, sometimes it will not display any channels until you configure the TV for your specific cable connection and scan for available channels. A channel scan can be applied to basically any type of TV or TV/VCR combo, even if you are missing its remote control.

Read more : http://www.ehow.com/how_6875646_do-old-tv_vcr-tv-remote_.html
Instructions

1. • 1 Bring up the TV's menu. Look for a button on the front panel of your TV/VCR labeled "menu" or "setup." Press it and you should see a menu appear on the screen. Part of the menu should inform you what buttons you can use to navigate through the menu. If not, try using the volume buttons or channel buttons on the front of the TV and see if pressing those allows you to navigate through the menu.
     
   • 2 Specify channel scan settings. Once you are able to navigate through the TV's menu, look for the "channel scan" "auto-program," or "auto-tune" option. This may be inside one of the TV's sub-menus such as "setup," "channel setup," or the like. The key of this step is to specify your cable settings before running your channel scan. The "tuner mode" option needs to be set to "cable" rather than "air" or "antenna." You may have to specify what cable type to use, this will be set to "std" or "standard" for the vast majority of cable providers. If you are not certain what cable type you use at home, contact the technical support department of your cable provider.
     
   • 3 Run a channel scan. Once the scan settings have been set properly, run the scan (usually done by pressing a "start," "scan" or "begin" button.) When the scan is complete, check to see if you are getting all of your channels. Contact your cable provider if you are not sure how many channels you are supposed to be getting.
     

Read more : http://www.ehow.com/how_6875646_do-old-tv_vcr-tv-remote_.html

good luck

Set the Channel scan for cable input, not antenna.

. Try putting you tv set to channel 3 or 4. Try your tv in all modes. Check the back also to see if in the right spots with the wires. Check your channel scan status, try it on anntena and try it on cable, run channel scan on both. good luck. Try vcr wires if cable wires dont work. vcr wires are yellow red and white. Try another cable cord sometimes they get old. Try looking at your remote and setting it to tv.

I WOULD SAY NO ! THE PICTURE TUBE IS PROBABLY AS MUCH AS THE TV IS WORTH. i had a very nice sony trinatron tv. the picture tube whent on it at about 5 years so I CALLED FOR REPAIR AND THE PICTURE TUBE WAS 2-300 DOLLARS. good-day !

Not a picture tube problem. Re tune the the TV by auto search or manual tuning.

Store your favorites later in your way.

The picture tubes in Zenith sets (I assume it's a Zenith since you posted this with a Zenith heading, although it's also true for any set this old) were only expected to last around 7 years. Your description makes it sound like you are missing green, or that the green is just way low. This is a common sign of a bad picture tube. There are other possible causes, but tube failure is the most likely. The low replacement cost for small TV sets makes repairing this one uneconomical.

Get rid of the set and treat yourself to a new one.

Don't use EZ scan,reset it to Factory Setting.Use Ch.set up go through the whhole process every channels should be there.

How old is the TV?
Sony Trinitron sounds like it may be from the 1980's?
Some TV engineers can use a piece of equipment to do a "tube boost" but this is sometimes risky and can completely ruin the tube, but it's a risk you would have to take.
If the TV is over 15 years old, and has been used regularly, (like 4 hours every day or more) it seems likely that the tube has reached the end of life.
TV cathode ray tubes are like light bulbs...they do not last forever!

do u have the user manual for the TV? if you do the solution will be in there, if not (I suspect you don't) please give the make an model so I can try to look this up, but off the top of head there is no way to "assign channels" to a paticular remote setting.