customize themes not working

[harryhansra]

hi,
i am totally new to this forum , i've installed customize on my i phone and i downloaded lots of themes , the problem is only a few themes are working most of the themes aren't getting changed , like when i go to customize- theme browser it shows lots of downloadded themes and then i click - apply theme to device , it shows- applying theme------ i go back to home screen it shows some changes then it goes to lock screen but when i unlock it nothing has been changed ......................... please help soon.........