I can't write more than one line on signs

The problem starts when I want to write on next line once I press enter it doesn't show is on the next line now if I press one more will pass to the next however if I press again will pass the next until I can't write anymore as always I have to specify my device is ZTE blade v6 plus I hope fix this bug a video shows what I'm talking about if does shows I'm trying to show it