Why my screen is gliching after changing the digitizer or display?

Recently I have changed the display of my XZ due to some touchscreen problem.after changing it everything was good when using for normal works like calling or browsing.

then I started to play games like Clash of clans or anything,the screen keeps gliching where the colours were more detailed.

then the problem started to be seen while seeing photos or videos.then when browsing anything detailed or colourful.The problem is increasing.

what is causing the problem?is there any problem in the connection of digitizer?because when I tried to take screenshot of glich,it was fine.

what to do now?