On Samsung models they call it "shop mode" and you change that to home mode. It may have another name. I didn't find the user manual so you have to check for this or similar feature.
This shop mode would do something like that.
I have a 3 years old LG Led TV, 32' FHD with Netcast system. It's plugged to a power strip, which is turned off every night for power saving, so the TV is in fact unpowered for about 8 hours every day. The first time I turn on the TV in the morning, it prompts the initial setup, as if it is just new and at the first start. This happens every day since 3/4 months, and is quite annoying, because I have to syntonize the channels, plus setting language and password, every time. Sometimes this happens also when the TV is in standby for some hours, but with power strip on. Any idea to fix this? Can it be a internal battery that has to be changed? Something similar to BIOS battery in PCs. Thanks in advance