Television changing on its own

https://www.techradar.com/news/pluto-tv-everything-you-need-to-know-about-the-free-tv-streaming-service
What to do when the television automatically changes channels, video inputs or volume?

1. Take the batteries out of the television remote control. ...
2. Turn off the television.
3. Unplug the power cord of the television from the AC outlet.
4. Let the television sit without power for 2 minutes.

https://www.techradar.com/news/pluto-tv-everything-you-need-to-know-about-the-free-tv-streaming-service

hello, are you referring to the volume of the TV set when you change channels? to reiterate every time you change channels the volume also changes? in this case I do not want to speak too much but I'm almost certain that television providers are required to adhere to a volume leveling standard which would require television broadcast stations to broadcast at a certain volume level for unity. Are you watching cable television? I happen to know that not all cable television providers level they're broadcasting some do.I notice that you are using a CRT unit are you attempting to use a converter box with the unit? If you are using a converter box there may be a chance that volume level is one of the options in the menu, I can not say there is much at all you can do about this.
As an alternative your television set maybe damage and the volume maybe adjusting randomly or in a way other than intended.

Good luck and thanks
Questions? Just ask!

When heats up, the supply voltage from the main power supply board goes less. Check all the soldering to this board for any loose solder terminals. Resolder all the suspected solder terminals by applying a little more solder. If it do not help you, replace the board as card basis.

Try to replace the remote control with a new one. If it doesn't work, then there is something wrong with your TV.

unlock the child lock

Well there is still a problem with the TV. I found that by unplugging the power cable that the digital channels worked. But, when I turned the TV on today the problem had returned, I had to take out the power cable again!

Do you have CFLs on in the room or adjoining rooms?

I have one in my shop with the same problem. Power is the only function that works. I repaired the power supply six monts ago. Now it looks like a bad digital processor board which is non-repairable. I can't believe what's happened to the tv business. Absolutely disgusting!

can not change channels

your TV is having problem in the power supply area or th secondary power supply where the micro processor is situated.take it to a qualified techn to be repaired.