I installed a baby gate at the bottom of the stairs to prevent my dog going upstairs during the day, he is still quite young. However I thought I had been accidentally leaving the gate open as I saw him comming downstairs a few times. It turns out he has actually been opening the gate he knows how to do it : /. I thought I was having memory problems and forgetting to close it.
Even my dad struggled to do it the first time when he came round