How to change from Night to day? it's always on night time

Hi all, just wondering how do you change from night to day, my son has a disability and he doesn't like playing in night time on plants verses zombies all the time. it seems to be staying night time all the time. Very frustrating as I haven't found anything on the internet to explain this about the game, sorry if this question has already been posted here. Any help with this is appreciated.