Is there anyway to lower the back headrests so they sit flush with the seats for better visibility. I can lower the middle headrest but not the two near the windows. There’s a video that shows it can be done by pushing the seat up, pressing the button and then hitting the top of the headrest. This doesn’t work for me?

 

Same here, the trick works on a GLB, but not the GLA. If anyone finds a way to do this, please post it here.