Sometimes the screen image on my TV will roll, but my set has no vertical roll adjustment. How can ....

The TV has to lock the image on the screen to a pulse sent at the start of every frame. If the picture rolls, then either the TV is trying to show the frames too quickly or too slowly (possible if the TV is an old one, and the values of the parts have drifted), or else the TV can't find the pulse telling it where the top of the picture is.
In either case, improving the signal strength should help the TV lock onto the pulse at the start of each frame.
Look for ways of improving the signal strength.
You can buy small TV signal boosters.
There may be a fault in the system that provides your TV (if an antenna, you may need a bigger one).

I had a tracking (or rolling) picture problem when using the DVD mode - the picture was also in black & white. Note that the picture did not roll when using the TV mode. After much studying and squinting, I figured out that the "TV Type" was set to PAL (European video standard) instead of NTSC (American video standard). As soon as I changed it to NTSC, the picture cleared up and the DVD played fine. The challenge with fixing this issue is that you have to change the setting while the screen is rolling - not easy to do. To fix, press Setup while in DVD mode. Press the right arrow button 4 times to "Preference Settings" - if you squint tightly you may see this title on the screen. Press "Enter". Press the right arrow button until you see NTSC - if this is the problem, the screen should immediately clear up.

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Hi, There is a button on your remote control which use for switch video system.