Why doesn't my tablet screen system take the exact place after getting a new Android?

[AC Question]

why my tablet screen system don't take the exact place after getting new android?

i reinstalled may chineese tablet DICRA tab710, when i reinstall it with microsd card ! it gives me an un equilibred screen ? i don't know how to fix it !
details :
Tab name : DICRA tab710
Android : 4.0.4
Screen : 7"