When I turn off one of my TVs, TV shuts off for few minutes then shows a background photo image

The situation you describe is the set top box remains on when the TV is off. Maybe you're pointing your Uverse remote in a direction that the TV receives the signal but the set top box does not.

It could be what Pedro is saying but there are a couple of other possibilities:

When you use the POWER button on the remote, you are asking it to turn off/on both the TV and STB/DVR.  If you move the remote too quickly, it doesn't have time to do both tasks.  Hold the remote in front of the TV/Box for about 2 seconds.  It should turn off the box and then the TV.

Second, make sure the ATT button on the remote (top left) is lighting up when you use the POWER button.  If it is not, press ATT then OK to make sure it's controlling the box and the TV.

@johnsjohnston - The previous posts are good descriptions of the situation. You may be wondering what to do about it

1) If you are turning on to watch & you get the OK message, it is pretty obvious - hit the OK button

2) If you are turning them off & the TV goes off, but the u-versse box is still on (green light). Hit the power button again to reverse the two & the OK button & the power again to try the turn off again.

In summary, the power button is always going to reverse both existing settings (unless it does not work). The OK button is the only way to break a mismatch.

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@aviewer wrote:

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In summary, the power button is always going to reverse both existing settings (unless it does not work). The OK button is the only way to break a mismatch.

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Spooky Jedi Voice: "...there is another..."

If you have an S10, you can press the TV button, then press power, to toggle the power state of only the TV and not the STB.  But be sure to press AT&T afterwards...

"...become one with the remote, Luke Skywalker..."