Hello really just wanted to have your reply first .
I`ll start by saying that this situation is somewhat normal when the hdmi control is set to ON , when the receiver detects activity from the tv`s HDMI input it switches by default to tv/sat input where it assumes the cable box or satellite receiver would be connected .
Is there anything connected there by the way ?
One way to change that would be to turn off the hdmi control but then on some receiver it also turns off the ARC function , if this is not the case on yours then by all mean set the HDMI CONTROL to OFF and that should take care of this problem.
Another possibility would be within the receiver's ANYNET / HDMI CEC function which is another hdmi control from Samsung and often causes problem with different controls systems , it is on by default so try to turn it off in the TV's MENU>>> SYSTEM>>> ANYNET (HDMI-CEC) >>> OFF and that may just do the trick.
Finally if nothing is connected in the TV's TV/SAT input then connect your direct tv there , that is where the receiver expects it anyway and why it switches there when it detects you watching tv
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