How to handle lying

Woke up and my 5 year old was watching the tv by himself and as soon as his dad walked into the room he shut off the tv. He’s been waking up before us and going straight to the tv. He was watching YouTube when he knows he’s not supposed to. Going to have to lock the door to that room but I am worried why he is hiding things and lying now. I get that some of that is developmental but I don’t know what’s normal and what’s excessive. How do you handle lying with a kid this age? We are putting parental controls on the tv today but I didn’t think we needed it until now. He has started to say things like “how did you know?” Even when I was in the same room as him when he did a thing he wasn’t supposed to do. This time it happens to be tv related but he does it with other things too. Like lying about flushing the toilet. I don’t want to shame him so that’s why I’m so lost on what to do. I was shamed A LOT as a kid, and any mistake was something “satan” made us do so I don’t have a good example as to how to handle lying at this age. It terrified me thinking that bad spirits were all around me trying to get me to do bad things so I didn’t do bad things out of fear. Don’t do bad things or satan will get you, was essentially how I was raised. I do not believe in any religion now so exploring ways to parent that do not involve religion is hard but very important to me. *not bashing religion or religious people this is MY experience.” Thank you if you have any input.