This is a great game! Well designed so that simple mechanics can result in complex behaviours creating some genuinely great puzzles. The concept is fun and pretty meta too and the art is just great!
I agree that the signs should persist after death. The only other thing I can think of is perhaps making it more clear how the screens connect in each level - one solution may be to replace the camera icon with NESW style arrows. Though this is a very minor complaint as great effort has clearly been put into making this clear in the level its-self.
Overall though this is a great game and I enjoyed playing it a lot!